Josiah Solomon - 2020-02-27

I think I found my answer

User Defined Encodings
You can also add new encodings to the set that FontForge knows about. There are three menu items that manipulate a set of user defined encodings. As always these specify both a character set and an encoding. The encoding has a maximum of 256 entries, but the character set may be larger (up to 1024). This means that you can define a font with extra characters. Since postscript fonts can be reencoded at runtime this can be useful.

The Load Encoding command allows you to load an encoding(s) from a file. Currently the file must either be in the format used by the unicode consortium for mapping ISO 8859 encodings to unicode, or it must be a postscript encoding array. The first format looks like this:

0x20 0x0020 # SPACE
0x21 0x0021 # EXCLAMATION MARK
...