You can't hack the spell speed. There apparently is a way to do it - some sort of program that lets the custom firmware PSP work on a TV under certain settings actually removes the spell slowdown, but nobody really knows why, and it slows down everything else to do it.
Further, you need these things. There is literally no way around it, unless you're an ace programmer who can whip up his own custom firmware, then deconstruct the PSP and put it on there somehow. You can try asking someone who has these things. Once someone's PSP has CFW on it, hacking other PSPs becomes a joke. (Set Battery -> Pandora Type. Copy modding files to your own Memory Stick. Use them properly and wait maybe up to two hours for everything to be reprogrammed.)
Unless your PSP is the -3000 type. Then you get to play the randomchance with the program that *sometimes* turns on the custom firmware... every time you turn the PSP on. And it seems to be a 20% chance or worse for it not to freeze the PSP instead.