I don't personally have any experience converting them. I have seen them used as a MLT. I'd ask around and see if anyone has done a step by step for the rubber ones.
Tap#1 Summer Saison
Tap#2 Amarillo Pale Ale
Primary English Mild
Secondary -Vanilla Chai Mead
Kegged Haüs Hefeweisen #4, Speckled Heifer Cream Ale
Bottled - Cherry Oatmeal Stout, Burbon Vanilla Oatmeal Stout, Blueberry Hefeweisen, Stubborn Baby Pale Ale,