Possibly. My original idea was that you had a list of powers for each level that you always had access to, aka the whitelist. Then, if you want something off the 'ban-list', you have to take a feat. This feat will give you a single power (subject to DMs approval) from the ban-list, up to one level lower than what you can manifest. There then would be an epic version that allowed you to use level 9 ban-list powers. Here's examples of my thought process.
Honestly, I haven't posted it in Tallal quite yet since I'm still working on the crunchy bits, but I'll post something about it here in a moment, just for you.