The other thing that occurs to me is the old drumset trick of mixing in a compressed version with the original. You set up the compressed version to have really sharp attacks. It doesn't work on its own, but the combination is great.
I'm not sure whether that would work on timps, although I've done it with old school samples on regular instruments, and it works well as long as you're careful with delay compensation.
There's also Waves Transient Designer, but I haven't tried it.