I haven't used SuSE, but I can give you some basic guide to help you.
1) Correct - you need cross cable if you're connecting 2 computers directly
2) Choose IP's for both computers
for example 192.168.1.1 and 192.168.1.2 with netmask 255.255.255.0
3) Asign IP's to network interfaces (usualy eth0 for first ethernet adapter, but may wary depending on network card type)
Commands I would use on my computer is ...
#ifconfig eth0 192.168.1.1 netmask 255.255.255.0
on first computer
#ifconfig eth0 192.168.1.2 netmask 255.255.255.0
on second
that should work.
If this didn't help, then use google and search for keywords like "suse network yast configure" or similar and it should bring you to some help