They thread directly onto your 1/4" MFL fitting. The Bev Seal slips right in the other side and forms a seal.
On the shank side, replace your standard barbed tailpiece with one of these MFL tailpieces and you're all set (assuming that your current shanks have a removable tailpiece held on with a beer nut and rubber washer).
You'll need 2 John Guest fittings and 1 MFL tailpiece for each tap. Certainly not as cost effective as the brute force method you're already familiar with, but worth the cost in my estimation. Cost for me was just under $40 to outfit 3 taps with the above hardware, not including the Bev Seal.