Indeed they seem to offer Silabs USBXpress to skip the UART
http://www.eetindia.co.in/ARTICLES/2007APR/PDF/EEIOL_2007APR27_NETD_AN_01.pdf?SOURCES=DOWNLOAD may be of interest and perhaps Softx could use this with an alternate version of VVP if it chats to the device any better?
I see the install also installs a folder with V5.0 of the standard USB drivers
Automan.