if you need to have something compatible with VB6.0
y not use crystal reports 9 instead of 8.5 ?

It is really a good Investement (i have been working with crystal report 9 for a while )

I think you will have to rebuild your reports
i don't think there is something like a migration tool or something
Best of luck doing that
I will be glad to offer help if i can
but i have been working mssql2000/vb6.0/cr9