Well sorry, but I see no way around it.
Also, there are only drives up to Z unless you do drive mounting.

How to create and use NTFS mounted drives in Windows XP
http://support.microsoft.com/kb/307889
 
You could use a .ini file to do the read group stuff but not much different than having it in the code

If InGroup('MyDomain\AA)
  USE USE E: "\\SERVER\AA"
EndIf
 
If InGroup('MyDomain\BB)
  USE USE E: "\\SERVER\BB"
EndIf
 

and so on and so on.

If you don't want to do it in script then at the machine map it as a persistent drive and don't deal with it in the script. The OS will map it each time it logs on for that user.