zypper ar obs://X11:RemoteDesktop:x2go/openSUSE_12.3 x2go
openSUSE_12.3 by the tag for the distribution you are actually using. Available ones are:
SLE_11 (SLES 11 SP2).
Congratulations, you are now able to access the X2Go packages. You may continue by installing
pyhoca-gui or any other of the available packages.
zypper in x2goclient