Like you, I also wondered if just direct heat/hot air would loosen the glue in a joint. I was a little nervous to try what Steve had done with the steam (I even bought a used expresso machine at a yard sale for a buck...but never took it any further...finally threw it away!) So I tried heating the area with a hair dryer (I've got a heat gun but thought it would be a bit much) and I started on Med. for about a minute...then kicked it to High for another minute or so...then with a few light taps with a plastic headed hammer...the heel came right off....
I thought "Wow! That was easy!"....So I tried it on the fretboard....working at the soundhole end I took my time and heated just a little of the fretboard at a time, working in a wedge as I made my way to the nut and......Presto!
Now I know I'm making it sound super easy (maybe since the guitar probably didn't sell for a $100 new....very little glue was used!) but I think dry heat may be an alternative to steam!
Has anyone considered this?
I have on older mini travel iron I use. Perfect size for a bridge or fretboard tongue. I just took the kinda flimsy plastic handle off & screwed a piece of square aluminum on for the handle. This pic isnt mine, just a grab off the net. I think it was $2 at a second hand store. The pic title says 'sanyo portable travel iron' but I dont recall mine having a brand name anywhere. A cheap useful little iron. Ive even used it for a few side bending touch ups now & then.
Oh yes, I use a travel iron for heating when removing bridges and loosening fretboard ends. The travel iron is light weight, so I use a small bag of sand over it to keep it in place. And some cardboard to protect the guitar, just in case .