How do I create a TrueType font from a bitmap image? FontForge seems to be able to do this but I haven't found a proper guide on it.

http://fontforge.sourceforge.net/editexample.html

Indeed but I will not recreate all 446 characters in FontForge when I have a perfectly fine bitmap character sheet with a grid. Is FontForge really unable to read simple bitmap character sheets? I have a ~30 line Java script that can read bitmap images and print the font perfectly. FontForge really should be able to do that.

Font Creator accepts both bitmaps and vectors for import and has a build-in tracer for bitmaps.
Having said that, as The Kat is a curious Kat, where can I see that script?

why not ScanFont ?

Fontforge use Python.

http://old.nabble.com/Fontforge-f1093.html