Multiple IPv6 PDs

Is it possible to request multiple IPv6 PDs, specifically multiple /64 PDs? I am on OS 3, but can upgrade to OS 4 if needed.

My ISP presently limits a PD to a /64, but suggested a workaround. They will assign multiple /64 PDs if multiple are requested, each with a different IAID.
However, I cannot figure out how to request multiple /64 PDs for my multiple VLANs. Any hints?

First, upgrade to TOS 5.