I would think neat's foot would work fine. I've been using it on baseball gloves for years. I'd probably put it onto a cloth rather than directly onto the bellows though. I use pledge occasionally on the outside of my cameras. Shines them up nicely but also seems to take off some of the black. I don't know that I'd put it on the bellows, although I suppose if it doesn't harm the outside the bellows would be fine too. Most of my bellows are still nice and supple - usually all I do is dust them using a dry swiffer pad.

Dan