I've the same problem fitting a rear mono unit. I called JHP who put together all the bracket conversion bits for me (£20) and now I'm waiting for it all to arrive.
I've been on the lookout for a suede pad for ages, and after missing loads on e-bay and on here I bit the bullet and bought a genuine Ducati item.
Standard seat £60 ish
Suede seat £100 ish
If the mono unit is not a Ducati item, then epoxying the bracket in place is probably your best bet.
[Edited on 4-6-2004 by Mr_S]