If you're referring to forwarding by setting up a rule in Groupwise to forward to your blackberry email address, I have this same setup and it works fine without POP access enabled. If you instead mean polling your GW account through the BIS, then the above poster is right-on; no polling without POP access enabled.
An irritating "feature" of Groupwise it that email forwarded to my BB has my GW address as the "from" address, making replying to the original sender a major headache. Also, attachments are stripped out of the email. By changing the rule to "delegate" instead of "forward" I can receive attachments, but the email _still_ appears to come from my GW address and the original sender's address is sometimes removed, making it difficult to determine who sent what. This "mail from my address" issue can be corrected by adding a switch to the GWIA, but my mail system admin doesn't like me enough to do it