Instant Scenery question

I'm looking at purchasing Instant Scenery. Does anyone know if you make your own buildings or can you only draw from a stock library? I've found Whisplacer as well that is freeware, but that looks like you can only draw from stock buildings.

There is a terminal I found for FS9 that I would like to transfer to an airport in FSX. Can this be done with IS - if at all?

Thanks 🙂