Lemme see if I'm translating this properly...

1) Your technicians are logging into your (assuming WinNT 5 or 4) workstations as the local administrator.

2) They connect to a share (and thus must supply their logon credentials to connect) and perform an install.

3) This installation is started from a KiX script and you are trying to capture the username of the user running your script.

How close am I?