Hello,
It probably never shows up because you're trying to use CSNW. I'll bet you'd be able to do it using the Novell client. CSNW is deliberately-crippled crapware(tm) that I wouldn't use for anything as important as backup unless you paid me much more than I'm worth and formally absolved me of any responsibility.
ARCserve 11.1 says in their instructions to install the Novell client on the Windows backup server if you're going to back up NetWare trustee assignments and NDS/eDirectory. Not CSNW, but the Novell client. And this is especially true if you're going to use the TSA's, which you should do if you're going to back up GroupWise. CSNW is just too brain-dead.
Be sure to install the Novell client custom, making sure to deselect everything other than the client, especially NMAS. Make sure you get the latest SP of the client, which at this moment in time is SP2. The download file of the full install of the client including SP2 may not yet be available, so you may have to install the SP1 version of the client and then apply SP2 to it.
By the way - the GroupWise client SHOULD be all you need to connect to GroupWise, unless it's such an old version that you can't do client/server mode.
Hope that helps
Ronny