While it doesn't produce executable programs for the PSP as of yet, it does compile and is a great first step toward having Irrlicht-1.5 on the PSP. Here is a link to the engine with modified source. Please note that the makefile is a shambles, and I would like anyone that knows make files to look it over and make it work properly. I also would like to see if anyone can further modify it to make executable programs for the PSP. I'm not entirely sure where the problem lies. It requires cygwin with the PSPSDK tool chain installed. You can get the toolchain from http://www.ps2dev.org. You can get my Irrlicht-1.5 source from:
http://www.megaupload.com/?d=DQOTHJW5