KanaSolver is a software that I wrote for human UTAU users, it allows you to convert Japanese voicebanks to Romaji voicebanks, and allow conversions of ust files too.
Download V2: Click to download.
The links below are old and obsolete versions and not recomended, but if you use it, you will need to set your pc to japanese locale:
Original version: Download
English version: Download
Background image from http://static.zerochan.net/UTAU.full.960511.jpg