In case you didn't know, there is a thriving community of PSP hackers out there, coding away to make their own homebrew apps and emulators playable on the PSP. My personal favorite is a chess game. Up until a little over a week ago, this was only possible if you had a Japanese PSP with version 1.0 of the firmware on it. However, if you are the owner of an American-bought PSP and you haven't made the mistake of downloading and installing the v.1.5.1 firmware upgrade that Sony has sitting in the pipe, then you'll be glad to know that some enterprising hackers figured out a trick to get all these homebrew games working on your PSP with a simple swap of your Memory Stick. Unfortunately, the app they wrote to split the files for the necessary swap was Windows only.
Thankfully, RnSKSoftronics, the makers of iPSP, have put together a Mac program capable of doing the same: HomebrewPSP Converter. Even better: it is free.
I think any minute now we can expect an updated version of this that will automate the new swap-less workaround for running homebrew games on your PSP. Until then, simply use this program to split the eboot file into two versions. Put one on one Memory Stick, the other on a second Memory Stick, and navigate to Game—>Memory Stick on your PSP, hit X, select the file on the first Memory Stick, and once the PSP game animation flashes, quickly eject that card and stick in the second one. Have fun playing your homebrew!