Not sure if there is another solution, but what I would do(using GIMP) is import my desired font and copy+paste my text, then chose text-to-path, then path-to-selection, and finally bucket fill or copy-paste my texture/gradient/shading into my selection(might also try multiple layers if your going for a "3d" look).
...I guess if you are trying to do this in a game(or custom program), you will have to do some programing, starting with the edge-detection to get the outline of the font you are using...