First, you need to get a v9.0/9.1 serial, since your v8.z serials will not work. Veritas doesn't sell them any more, but yhou can usually find a few on EBay or the other auction sites. I think I also saw some at isellsurplus.com
Then just install ove the top of your v8.x code and everything should be migrated forward.
And I'd go straigt to v9.1 SP2. SP3 is out, but appeares to be a little flakey so far.