I'm the author of Optimizer a small Zaurus filesystem utility that was once a retail product.
I've decided to make the last version that was released, 1.0.6, freely available. It should work with the standard Sharp ROM and Jeode or Sun's CVM, and was tested on SL5x00 and C series Zaurus, although it is highly compatible, I even had it on Jeode on PocketPC at one point, but you may need to play around/tweak it to get it to work now.
Read my blog post for more pointless details/disclaimers, link is at the bottom of it:
Benjamin (Silent Software)