Forceing suse 9.1 to use icewm over KDE

I am just rebuilding our LTSP server, (which had a hard disc fail). The last time I editied one of the config files to force execution of icewm, regardless of what the student clicked in kdm, but I cant remember what I did! Is there a) a cleaner way of doing this? something that didn`t require hacking of scripts is much easier to document. b) what am I likely to have editied? I thought it was //etc/X11/xdm/Xsession, but that didn`t "look" right. Thanks Rob Keeling