openSUSE sets the firewall configuration thru SuSEfirewall2.
I don't see, on the referenced opensuse page, where an iptables config is located for opensuse. I do see a sentence that tells us the default iptables location is NOT the opensuse location.
So, on my two opensuse 11.2 machines I do (command line)
I get back
iptables: /usr/sbin/iptables /usr/share/man/man8/iptables.8.gz
That just tells me where iptables is. I try SuSEfirewall2 and
Because I'm messing about with this myself right now, I know openSUSE sets the firewall configuration thru SuSEfirewall2. Yast just sets the configuration there. Theoretically, you could disable the firewall in Yast, and use an iptables script, I suppose, but it seems to me that a lot of suse setup looks for susefirewall2, and I think it quite possible that writing your own could lead to something getting undone. I am not sure.
You COULD use the SuSEfirewall2 config file to set iptables, and that not only should work, but seems to be encouraged by suse. Check the openSUSE site for more info.