Apologies for the temporary deletion - I found an error and needed to correct.
OK now (22/6/12)

The Following was on My SLK32 - I cant verify if its exactly the same as the SRT 6.

Ok - I've drained, blown out and refilled the "Charge Air Cooler" and Intercooler Coolant.
Someone mentioned needing to blow out the cooler - others may have achieved this also - here's my technique pictorially and below.
As mentioned below I did the main engine coolant 3 days ago refilling with Blue instead of the previous Green coolant. With this - I was hoping to assess the degree of intermixing through the colour difference with the old charge air coolant being green. Unfortunately the blue in the reservior has mixed, but I'm convinced that there was only minor mixing within the 3 days (30miles). See colour photo.
I was suprised by how little coolant there was in the charge air cooler (white dish photo). I reckon I got about 2L out of it in total. Hard to tell 'cause I needed to flush the system out with distilled water (pictured) through the intercooler to the pump.

To Flush the Cooler and Intercooler through to the pump .....

Make Flush Bottle
You'll need to prepare a sealant nozzle (or similar) and a 1.5Qrt soft drink bottle with distilled water.
Note - the Nozzle will have to fit into the end of smaller rubber expansion line tube going to the main radiator expansion line.
Before you totally fill the bottle with distilled water - flush it completely several times with clean tap water or demineralised (if you have it).
Then place about 200mls of distilled in the bottle and give it a good shake and vigorously shake out (discard) - coating all the insides of the bottle.
Repeat this shake out again, 3 times if possible.
Note - there is almost 10 times (ie: order of magnitude) difference between the quality of distilled versus the quality of demineralised water).
Fill the bottle with distilled water
Insert the nozzle and tape it up so that it doesnt leak.
Okay lets get into it.

The Job
Part I - Drain
-Jack car and remove RHS front wheel
-Remove fender interior
-Place low level dish >2 quart capacity under pump suction
-Disconnect the system at the pump suction (pictured Point A in schematic) - you can get to this from underneath, but easier from the wheel well I reckon 'cause you have a bowl in the way.
-A little dribble will come out.
-Open the Reservior Cap, breaking vacuum and allow to drain - about a litre will come out, wait until it slows to a drip.

Part II - Flush Charge Air Cooler
-Put a rag on the alternator to protect from drips
-Break the line at Point B in the schematic/Photo - where it joins the aluminium charge air cooler hot outlet hard pipe.
-Plug the aluminium section with a cork - I've used a sealant nozzle (photo). Make sure it wont leave any foreign body in the pipe when you finally remove it (later).
-Remove the thiner expansion reservior hose from the "T" where it joins into the main radiator expansion line. Clean this 'cause you are going to use your mouth to blow through it.
-Place the nozzle of the coke bottle flusher you made earlier into the expansion line to the charge air cooler and allow half of it to drain into the charge air cooler and through the lines to the dish.
-Remove the flush bottle, and take your mouth and blow through the hose - this will blow the water through the charge air cooler, through the hot side hoses and pump to the pump sucton.
-Refit the flush bottle and run the remaining flush water bottle contents into the charge air cooler.
-Blow again repeatedly until you are confident it has blown all the way through and sounds empty.

Part III - Flush Intercooler
-Refill your flush bottle
with distilled water
-Back under the car at the pump put another bung/cork into the rubber hose that goes to the pump suction
-Clean the top of the hose at Point B 'cause you are going to put your mouth on this later
-With the nozzle, run all the Litre/quart of water into the rubber hose (B) that goes to the intercooler.
-Note - you'll hear gurgle and carry on as it fills the intercooler, but dont over fill as it could start going back to the expansion tank and mix with your engine coolant. Just a Litre/quart.
-Remove the bung/cork and quickly blow into the hose at point B - you are blowing through the intercooler to the pump suction.
-You're Done!

Part IV - Refill
-Reconect the thinner radiator expansion hose to the "T" piece.
-Reconnect the pump suction pipe under the car.
-Do not reconnect the Hot Water Line (B) just yet - that's your air bleed....but make sure its higher than the level in the expansion tank - otherwise of course the reservior can later run out through it.
-Make your coolant mix to the recipe you desire....
-Take a note of the expansion tank internal "riser" level (from the charge air cooler coolant line) - see photo.
-Fill the expansion tank to the top with coolant mix
-Wait 5minutes and top up the expansion tank when the level gets back down to the level of the riser tube.
-You can do it again - but by this time the pump should be submerged (primed) and we should have a good chance of kick starting the system.
-Remove the cork/bung - some drips will run out onto the rag on the alternator.
-Reconnect the hot side hose to the aluminium feeder pipe to the charge air cooler.
-Remove rag from alternator and cleanup spillage (if any).

Part V - Back Together - Run
-Refit fender liner, replace wheel and cleanup in preparation for an engine start.
-Start car and allow expansion reservior to makeup for the losses.
-Top up if required.
-Keep a Litre/Quart of coolant mix in the car for later - in case your coolant light comes on.
-There arent any graduations for max/min on my reservior - so others may comment on the level required. But if the coolant level light comes on - top up with another 200mls.

Part VI - Bleeding Residual Air (If Any) - (copy from eurocharged cooler procedure)
- After doing the above, run the motor over several heating and cooling cycles.
- Once the motor is finally cool, remove the expansion hose (to the reservoir) into a suitable container.
- Being careful of pulleys and moving parts....with the aid of an assistant, have him raise the RPM to just above 3000, while you gently close off the intercooler fluid return line (red). When only fluid (with no air bubbles) is observed being discharged, you're good to go.

Hope this all helps someone else.