Is there a way to override the use of maxVersion in firefox extensions so if a new firefox update comes out the extension will still work? I think this can be done by setting a new bool in about:config but I am trying to do it from the extension itself.
I don't know a way to do it only for a single extension, and it really doesn't make sense. Inevitably, it will eventually stop working. You can set it to an arbitrarily high value, though:
<em:maxVersion>100.0</em:maxVersion>
This means you can't distribute it through AMO (for good reason), but you're free to do so independently.