The simplest solution is get another job.
Ban on cellphone use when airborne is probably not aircraft safety but the phone latching onto multiple relay stations and obstructing the network. This is easily detected and if it annoys the network operator enough you will get a snotty letter at least.
What they are asking you to do is downright dangerous. Me, I'd just walk out. Life's not worth that sort of (very considerable) risk. And while you're at it shop them to their insurance company - that'll stop 'em.