If you and not going to enable SNMP on key devices, so that netmon can do discovery for you, then you are going to have to use a seed file.
You can read all about seed files in the NetView books (and there is much about them in the archives as well). You did install the books didn't you?

Basically you will have to include seeds from each of your major sites, and each of the switches/routers/gateways you want to monitor between them.

Seed files are also how you deal with DHCP nodes. These get flagged in the seed file as well.

James Shanks
Level 3 Support for Tivoli NetView for UNIX and Windows
Tivoli Software / IBM Software Group