JP Sets
This hack would allow you to grant completely custom JP values (min-max) for every job given a specified "Job unlocked" job and level specified in FFTPatcher in the ENTD tab.
At the very least it should grant custom job levels for each job.
For example:
Jobs Unlocked Archer Level 255 could set Squire to lvl 5, Knight to lvl 2, Archer to lvl 7, Thief to lvl 4, Lancer to lvl 2.
Jobs Unlocked Unknown Level 0 could unlock all jobs at lvl 8
If proceeding with job levels only, the edit would be a simple override of the job levels normally copy/pasted from the SCUS.
In the case of JP, I think the job levels might have to be calculated first based on the JP range, then at the time of generating the JP amounts (Job level's JP + rand[0, 99]), override those with the new numbers.