I started digging through 3pp stuff to see if there were additional mythic paths that occult characters could use. I'm not sure what our GM's stance on 3pp is though (not sure if it ever came up). Note that I haven't bought or reviewed any of these, so I'm not sure how well they'd work for your concept.
There is a 3pp Transcendentalist path which appears to tie in well to psychic casting.
This one isn't paths, but it adds mythic versions of many occult spells: link
For first-party stuff, you could go with GM Rednal's suggestion and ask if it's ok to reflavor Archmage to apply to psychic casting. Marshal wouldn't be terrible, although it'd put you more into a support-type role as far as mythic abilities go.