You could back it up, boot into another OS, secure erase it, reinstall OS X, and restore your backup. The other option is to wait for TRIM support to show up in the OS. It seems that Apple's working on it, since some hints of it have shown up — notably, 10.6.4 added a "TRIM Support:" status line to System Profiler. Currently it always says "No", but perhaps that will change in 10.6.5 or 10.6.6.