Hi again,
Not easy, in fact practically impossible, unless he qualified in one of the shortage occupation skills lists that's issued by the UK Government; this link will take you there. Assuming he does qualify, then he would need to find a job with a company that is willing to sponsor his visa application. Even then, the UK Government have introduced regional quotas for all work based immigration, so if his regional quota has already been allocated, then even if he was qualified, found a job etc, he could still be turned away.
Hope this helps.
Cynic
Expat Team