We are planning to add universal approach to control this option for all rooted phones.
I would hardly say this is completed.. I would suggest you take the same approach as apndroid does and rename the apn setting from within "settings profiles".. If you use the same renaming as apndroid, things should stay compatible to this apn switcher but we can natively disable 3g.
Apndroid seems not to work well on a lot of phones. Also it would be more logical to implement it in a profile then as an external program.
If put in a profile, SP can show it in the notification bar and so on..
Duplicate of this much more voted request:
Would be much more logical, this way we can put it in profiles and it will show there.
For Android 2.1 and upper