Ok, I’ve found the drivers and the control panel for the Roland UA-100 on BeOS:
http://ftp.ntua.gr/mirror/BeOS/experimental/r5/drivers/audio/
http://hp.vector.co.jp/authors/VA022515/archive/ua100panel01.zip
The control panel also needs some files from the official driver of Roland.
The instructions are available here: http://hp.vector.co.jp/authors/VA022515/index_en.html#
The UA-100 control panel on BeOS (this ain’t my installation):