To work in Mexico, a foreigner should live in Mexico first, then find an employer willing to support their application for a 'working endorsement' to the appropriate visa; probably an FM3. The nationality of the employer makes no difference. The purpose of the law is to protect Mexican jobs from foreign competition, as most countries do, by requiring 'work visas'. If one has skills that are not available in Mexico, then the odds are better. Of course, fluency in Spanish would be necessary for most jobs in Mexico.