Not worrying about being sacrilegious... It probably is a logical place to ask. :-)
Question: Doesn't THERMOfoil mean heat is part of the process? Answer: Yes.
I've seen a thermofoil press in action. Here is my understanding of how it works. (If I have this wrong, someone please correct me.) It used a combination of heat to soften the thermofoil material and vacuum to pull DOWN the thermoil to the substrate. Also, a special adhesive was sprayed onto the work pieces (then allowed to dry) before being placed on/in the press.
A vacuum bag will remove the air and create a vacuum in all directions. The top of the bag will press down on the top of the part, of course. But, it may not pull it tight around the sides of the piece. Also, the required temperature to soften the thermofoil is probably past the limit of the bag material. And, I am not sure how one would apply the required heat.
A thermofoil press only creates a vacuum UNDER the parts, thereby pulling the thermofoil material tight on the tops and sides of the work pieces. It also applied a great amount of heat using heat lamps directly above the thermofoil material. Something I don't think you would be able to do with a vacuum bag.
I would suggest searching on youtube.com for "thermofoil press" and learn a bit about how they work. It is a bit fascinating, and is a relatively quick process for multiple parts.
If you are looking for a small thermofoil press, try: http://www.vac-u-clamp.com/thermofoil
I am not affiliated with that company. I just know that they have been around for quite some time.