There are two ways to get this working:
1. Build a tunneled (GRE) infrastructure through the service provider network and start running IP Multicast routing - no client configs but you must have a own router at each site (I'm running 20 sites in that way)
2. Configure the Netware Client with static entrys pointing towards the servers running SLP DA - i.e running SLP over unicast. This can either be done on each client or by a DHCP server that supports the Netware extensions.
Tip, look at theese TID's at support.novell.com:
TID 10025313 - Frequently Asked Questions about SLP
TID 10014396 - "SLP Terms and Configuration Reference"
TID 10014467 - "Configuring a LAN/WAN infrastructure for SLP"
TID 10014466 - "Configuring SLP for a NetWare Client"
TID 10027163 - "Configuring SLP for a NetWare Server
TID 10062474 - "SLP Design and Implementation Guidelines"