Ok so what's the top of the line phone for this?

Take your pick. I'm pretty sure anything S60v3 will work (assuming it has a decent CPU). Newer units might too, but I don't have one to test on obviously.

Sure, if you want to run it over a Bluetooth serial port. No idea what the latency would be like though.

It might just work. If not, then it should be pretty simple; UIQ3 is S60v3 with a different UI layer as far as I know.

This port is tested & working on a Nokia E63, which is S60v3 FP1. It should work on FP2 and MR (but might need recompiling), but I've no idea about later editions.

To get kicking, install all of the prerequisites, then grab the latest ghetto ghetto port build. Make sure you've enabled installing unsigned software.

If you want config or mapping files, put them in c:\data\lgpt.
Default keys are set up for a qwertyphone: left and right softkeys are the shoulders; green call is start; P and backspace are A and B respectively. Dumpevent is hardwired to on if you need to look up keycodes - look for the log in d:\lgpt.log (SD card, if you have one).

The audio infrastructure on Symbian is pretty crap. Some phones will respect the audio buffer size setting, and others won't; it defaults to 0 (OS default), and you can configure it in the usual way. This version also implements a sandbagging hack to get the latency down when there's no buffer control available; this involves delaying sample submission whenever the OS buffers get too fat. You can configure this with the config.xml option S60SANDBAGDELTA - defaults to 11500 which gives best performance on the phones I have access to; 0 disables the mechanism entirely. Too low will cause skipping.

For the brave and/or foolhardy, the source is on GitHub. At some point I'll clean up the tree to a reasonable standard.

This for sure isn't a popular platform nowadays, but I'm not the only person in my suburb rocking an S60 phone - and now I'm not the only one rocking a proper tracker on it either.