I have a gut-feeling this concept will work. Every workstation will run the script, and logic would be something like:

 Code:
if (this workstation is in scope for package A)
 install package A
enndif

if (this workstation is in scope for package B) 
 install package B
endif

etc, etc


Its the determination of "in-scope" I need to work-out. Unfortunately that could be just about anything ... from a simple list of hostnames to some other more complex criteria (like using the IP address). Will probably just custom code these IF statements as opposed to "softening them up" in an INI file like you did (your way is more eloquent imho).