What?! You doubted Qwerty the Pimp?! I must get my revenge by coming up with a hack to this problem!

Prerequisite:
fmtxd patched: fmtxd, using http://maemo.org/api_refs/5.0/5.0-fi...5a46afdad43a94, checks to see if you're in a call. So open up /usr/sbin/fmtxd in a hex-editor (I used vi on the tablet itself) and replace "sig_call_state_ind" with "sig_call_sttte_ind". Make sure that the transmitter isn't on whilst doing this and that fmtxd is not running.

1. Install http://talk.maemo.org/showthread.php?t=43395 (the fm_boost variant may be better, depends) (not required but you'll find it easier)
2. Unzip the attached somewhere.
3. Make a call, hit Speaker and turn on the FM Transmitter (you'll see why 1. makes this easier...)
4. As root, run "alsactl -f /speaker_fmtx_on restore" with "/speaker_fmtx_on" being wherever you placed that file.

Oh, the interference is a *****. I may write a daemon to make this easier.