With Zen7 it was easy to use the %CN% or %Username% to get the current users name for use in the NAL apps. There is no equivalent in installshield. I had a requirement to do this myself and eventually found a relatively easy way to do it. I documented this and posted it over at cool solutions.
I've noticed a couple of threads on here (quite old) where people are asking about this, so I thought I'd put the address of the document here in case anyone else is searching for this info. Hope it's useful.

USERNAME Variable in AdminStudio InstallShield | Novell User Communities