As we know from White Night, the only thing you need to become a freeholding lord under the accords is the sponsorship of 3 members of the accord. However, no White Council wizard in his right mind is going to help you on an endeavour like this. On the other hand, there might be some grumpy regional commander that needs a favour and is eager to bend the rules of the White Council as much as he could. From there you'd only need 2 more signatories, a short list of them is found in OW I believe, but I'd have to check.
I have been thinking about a background for a group, a sort of self help group for wizards that went down the bad road and were able to pull themselves back at the last second. The White Council would kill them anyway, so they do their own thing and try to find others like them and they keep each other in check as best they can.
If you are a member of the accords, you are going to have to answer to the accords first. However, I believe a lot of wardens would still see you as their responsibility and would hold you to the laws of the White Council without bothering with the accords. If someone would have a problem with that, they can challenge your executioner to a duel under the code duello, but I don't think any of the non-human members of the accords would even bother.
btw., I was going to suggest looking at Magneto until I read to the end