I'm looking into a different method but haven't had enough time with it yet to see how well it works for iguanas.
We have a ball python and it was having trouble shedding, especially on her eyes. The vet said we needed to up the humidity in her tank, so we took a large plastic tub with a lid and cut a hole in it big enough for her to slither inside, placed a damp rag in it and set it so part of the tub was over her heating pad. It provided her with a hiding place as well as a place to get plenty of warm humidity. It ended up working great for her.
I'm trying to see if a similar set up will work for the iguana.