Software Deployment

You can, but this is a whole different area of packaging. Basically, there are two types:
1) Adapting vendor's installations to MSI
2) Authoring MSI's from developer's code

They want you to do #2, but this site is directed at #1.

If the the app is simple, then you could probably do it without much trouble. Just ask the developers where each file should go and what COM info should be created for each DLL. Then build it and give it to them to test.

If you need direction doing this, I'd suggest using:
http://community.installshield.com/forumdisplay.php?f=162

Which is a forum more geared toward what you're doing.

One approach:
Use Repackager
take 1st Snapshot of clean system
place all files in appropriate locations on the wkstn, do whatever is necessary to manually set up the application and make it work.
take 2nd Snapshot.
then the rest is the usual: cull the resulting IRP of extraneous crapola and generate your ISM, make any final mods to the ISM, generate your MSI.

That approach might be good enough for a simple MSI that's only used internally and is well tested.

I personally would open a new MSI project and author it properly. Create the features, components, conditions, etc by hand. But if you don't have a lot of experience, Fosteky's idea might work for you. Test the crap out of it though.