There is an error in the “Roll Your Own Glyph Data” blog post. It says, in part:
“…you should see Temp and Plugins folders as well as a CustomFilter.plist file. If you do not see an Info folder there yet, it’s time to create it (Cmd-Shift-N). Inside, the Info folder, paste the GlyphInfo.xml:”
The file name referred to should be GlyphData.xml.