According to
optcorp, you can use it for the 10" and 12" LX90:
The new Ultrawedge for the RCX400 (10"-14"), LX90 (10" & 12") & LX200 (7" - 14") series is more rigid than ever
With autostar you go into the setup menu's and set the scope to 'polar' mode instead of 'alt-az' mode and it will work properly.