Thanks for this useful tool.
I just used it to update a Win2K SP2 install CD to add 48 bit LBA support by copying ATAPI.SY_ and UPDATE.INF from the W2KSP4_EN.EXE file made available by Microsoft. The update was done entirely with tools that are part of Debian Lenny Linux, except that I needed Jared (reg_imp) to edit the SETUPREG.HIV file so that 48 bit LBA support is enabled on initial boot from CD. Jared built just fine under Lenny once the appropriate packages were installed.
It would be really great if very minimal documentation were provided. Maybe I'm a bit slow, but it took me a while just to figure out that reg_imp was the executable program. It would take just a few lines of text to indicate where definitions of the top level classes are to be found. Of course the fact that I don't speak Java might have been part of the problem!!