I did the folow steps.
1.- Create a OpenVPN Warrior type TAP (why TAP?, because it transport protocols layer 2 like IPX)
2.- Open port 1194 UDP in NethServer
3.- Change Virtualbox (or VMWare) Ethernet cards to promiscuos mode (Because you will transmit Broadcast and Broadcast in VirtualBox and VMWare is disabled by default).
4.- Install Novell Client over Windows XP (because XP still have IPX protocol) with custom option,and choose only IPX.
5.- Connect to VPN and Open the Novell Client and search the trees.
Axel, The same IP segment is correct because you VPN connection is a Bridge Connection.
Done.