Yes you can add a UDF to the kix_functions.kix file and that will be available for the rest of the logon script.The UDF's are the first thing loaded., and since the custom scripts module is last.... 
The $runpath variable would be the thing to edit. it is used to define the location of all the other scripts.
Right now $runpath is being set from the logon.bat file to equal %0\..\, the current netlogon folder.
When i first wrote this script, early 4.0 beta, I did not have some of the commands available that we do now, so i had to create work arounds (EXPANDENVIRONMENTVARS being on of them.)
Bryce
