The airlines are looking for people who can qualify to hold Design Approval for structural repairs or stress analysis for cabin interior work. Make sure your CV demonstrates your capability in this line of work. Then find out who is in charge of Technical Services in your target airline and send your application direct to them. If they like the look of you, they'll ask their HR people to hire you.
How do you find out who's the Head of Tech Services? If you can't do that, you won't be able to hack the job.
Good Luck!