Do you mean that when you try to put in the freq. manually it automatically adjusts, like it is scanning for the best station? For example you are trying to put the station on 88.7 or 88.9 for the ipod itrip and it automatically tunes up to 90.1?
I bought my Crossfire used so I don't exactly have a manual either, but I do have a ipod/roadtrip adapter and had the same problem. I managed to figure out how to adjust the station manually. Let me warn you it is definitely annoying but once you do it. Simply set into the preset/memory station buttons and you shouldn't have to mess with it again. Like upstate said you turn the right **** (rotate it) to tune to different stations.

1- Turn on the radio, make sure it is set to radio fm station side.
2- Press the OPT button (found on the top row/silver button).
3- You should see a different menu on the screen now, it should say:
Dis Reg Pty Tun Rds Txt Tp

4- Select/Press Tun function and
quickly rotate the right **** and you should be able to begin to select the radio
stations manually.
5- After you have found the station you want 88.9 or 88.7 or whatever dead station
you can find select whichever memory slot 1-12, I believe. And press and hold for
a few seconds to commit it to the radio station memory. Repeat as necessary.

Hope that is clear.