Comment Don't use formal training, buy them a computer! (Score 1) 343
Buy a Mac for each of these guys to use at home. Put the Linux distro you're using on the Mac in a VM. Task them with setting up the machine to run remotely on the corporate network under both OSs. They'll have fun learning, and will then be prepared to support others.
The gift is also a nice way to reward them for their years of service.