For those of you who would like the functionality of Team M33's firmware on your Sony PSP without actually installing it (either because you don't want to or have a model you can't flash) here is Xenogears's and Becus25's Custom Firmware Enabler which will allow you to. Using the ChickHEN exploit you can install a lot of M33 type features which now includes the ability to boot POPS (PS1 games) under ChickHEN. While this is compatible with ChickHEN is sadly won't work on PSP-3000 consoles.
Read more about Custom Firmware Enabler v2.51 (PSP Application)