SqueakyClean
Sounds interesting.
How about coupling that with a basic English proficiency test? Nothing elaborate.
If they have a high enough IQ and pass the English test (and no criminal record), legalize them.
If they can't pass the English test but have a high IQ, they can have a provisional period of 1 or 2 years (experts determine a fair period), during which time they can study English and retake the test.