Standards for this vary, but I'm afraid none of them are very promising. For recreational divers, one common guideline is that if you've been seizure-free for 5 years and take no medication, you are able to dive, although you should avoid hyperventilation and high PO2.
There isn't a lot of hard data behind this, but the basic thinking is that diving probably lowers the seizure threshold (in part due to elevated PO2), and it's also possible that seizure medications may work less well at depth. Given that seizures at depth tend to be fatal, the guidelines are naturally conservative.
This subject is close to my heart, as tomorrow I'm scheduled for my first dive in seven years, following a single seizure. Given that I've been seizure-free for seven years, and that I've been off meds for five, my seizure risk isn't much above baseline. After consultation with a DAN-recommended neurologist, I'm cleared to dive with the following restrictions:
-no hyperventilating
-no elevated PO2 (ie, no Nitrox or deep air)
-informed consent from my buddy (since a seizure on my part would put them at significant risk)
One text I have handy contains the following passage:
Individuals with controlled epilepsy (taking medication, seizure-free for 2 years) are advised NOT TO DIVE. Should they choose to ignore this recommendation, they accept the increased accident risk.. In the climate of "informed consent", the risk may be accepted, but it should not be ignored.
I bet if you shop around enough, you can find a doctor who'll clear you to dive. I have to say, though, that while I sympathize a lot with your position, I think you shouldn't be diving.