I'd certainly be willing to recompile Pierogi for the Neo900 if needed.

I should mention that while IrDA uses the same wavelength as "Commercial IR" (what remote controls use), it runs at a much higher speed and a much lower power level. Although some folks have managed to retask IrDA LEDs to output CIR commands, they generally don't have significant range (half a meter at best). So, you may have to choose between IrDA or CIR if you're going to replace the IR LED.

Also, I'm not entirely sure there's enough room in the existing case to fit both an IR receiver LED and an IR transmitter LED (at least for CIR)...

EDIT: I should mention, if you're taking requests , it'd be nice to have an LED that provides a little more output power. In particular, the current N900 LED doesn't seem to have enough strength to communicate well with Sony TVs...