Maybe start ringing or emailing fitness gyms on his behalf in the area where he wants to move to.

Some may not have a boxing coach but might thinking of getting more into that side of fitness?

Have his full history in the sport typed out to give them and if they want him to work; get a letter of acceptation to the position so he can get a work visa.

Where is he from?

most foreign countries have there own social clubs, you could go through them as they hire their own more often.