I do know how to do that and I have done it but it consumes hell lot of memory, makes my n900 feel slow, high chances that I have to wait quite some time (50sec) before I see a call window after my ringtone has started to play, frequent crashes, tiny tiny tiny tiny font and what not and hence its quite a pain. I can only wish that someone port the j2me environment successfully (native rather than something like microemulator) and someone indeed tried a bit for that (porting it from s^3 to maemo) but its still a long way(or no way?) to go.