I've got the Server Update to 10.5.1 if that helps you out... not as much of a jump using ASU with the Combo Updates.

EDIT: http://rapidshare.com/files/12989895...rUpd10.5.1.pkg

ASU Mod this like you would any other pkg file in the Downloads folder. Should work.
Question... do the updated kernels (9.2.2, 9.4.0) work with the Server Version after the update from regular OS X? If this is the case would it not be possible to just use the mpkg (or combination of pkg files) to update an existing installation of 10.5.4 to Server?

Yep that's exactly what i've done, updated my existing install to server! I've had a few side effects which i'll iron out tonight. And yes the kernels work...

I'll be able to post more information when i get back from work in a couple of hours if you guys can wait till then ;)

Guide can be now be found here

that link rocked! :D thanx mate