Several sources are reporting that it does indeed work. You’ll need to do some funny trick with swapping Memory Sticks (so you do need two of them) and modifying the PBP file of the homebrew application you’re trying to run, but when all is said and done it will hopefully work for you. All necessary files, including a tutorial, are available… Link. Bonus link: PSP MAME is updated.
How to run homebrew on 1.5 PSPs