All you have to do is round up and deport fewer than a million, send several hundred corporate executives to prison, and make it virtually impossible to get any job other than cutting the lawn, the other 10 million will move themselves.
This is actually going to have the biggest impact on slumlords.
That's the way I think it should be done too. Save the money, we don't need a fence.
It's even easier than that, just have one or two high profile raids a week including employers doing the perp walk. Then have the head of ICE come on TV to ask the public to help in finding illegal employers.
This will scare those that hire illegals so bad that the jobs will virtually dry up overnight.
Then you can offer free transportation to the point of entry of their choice.