User blog comment:Crimson Storm Mich/Guide: Omni Evolutions: Cross Spark and Resonance/@comment-25025482-20160414030705/@comment-27371390-20160414063618

@SageBladeRigness

By extra customizations, do you mean the SP Skills?

It will only be unlocked once you get your OE to level 150 and with UBB. Upon fulfilling these two conditions  you should see something like this once the fusion is over:

After that there should be an "Enhancements" button above the "Switch".