Yes, you can put Rx damping pads on a BlackBery C-ring. BlackBery rings are slightly smaller than Rx rings, because the pads are smaller, so you might have to bend the rings open just a little to get a good fit that's not too tight. BlackBery C-Rings with Rx isolation pads generally don't synergize as well as with the pads that are meant for them. You never know though, every system is different and sometimes a result will defy the norm. I would suggest giving Preamp UltraSonics a try, though. They're probably pretty close or exactly what you're looking for.
Preamp UltraSonic and BlackBery isolation pads are each a little different yet interchangeable, so they can provide several combinations. You'll get slightly different results with different combinations. Differences will be not in tonal coloration, but in dynamic impact (definition, detail resolution, etc.).
SteveHerbie's Audio Lab