I am not completely sure, but if I think it all together in right way, I would say that those bump maps are nothing else but heightmaps. Programs like xNormal should allow to convert it to a normalmap while keeping most of the quality, but I think that even the gamestudio function bmap_to_normals or what ever it is called and those plugins for gimp and photoshop are converting it the right way and should thus result in a good normalmap when generating from a heightmap.
But you should think about some kind of a specularity map. In my opinion a greyscale version of the texture works quite well in most cases if you darken it and raise the contrast.
I don´t think that there is an effective way to use those bump maps in a modern shader, but I think that those dot3 bump mapping fixed function effects were meant to use such bump maps.
This is a in my opinion great article about different methods of bump mapping from 1999 when bump mapping was high tech:
http://www.3dconcept.ch/artikel/bump/index.html The "problem" is that it is german...
As I am already at it... This is a great glossary of 3d graphics:
http://www.ericchadwick.com/portfolio/glossary/glossary.html It is old but in my opinion great to understand and it seems to be very correct. This link is in english btw...