KDE 3.2.3 in GDM session?

[Andrew]

konstruct is finally done building KDE 3.2.3.I sit into ~/kde3.2.3/... I
performed all the README's 'After Installation' instructions and it
still load KDE 3.1-12a. I'd like to launch it from GDM...
 <http://developer.kde.org/build/konstruct/stable/README> 

My question is: How do I add KDE 3.2.3 into GDM's session menu? Detailed
instructions please. I want to see both 3.1-12a and 3.2.3 listed into
GDM.