Modify the can and extend the hose all the way to the bottom of the tank. Exapnsion and contraction of the coolant as it heats and cools will fill the can, then the radiator will suck it back up through the same hose coming out of the top. This is how the stock catch works. I think the tank does need to be open to the atmosphere however.
'99 Jeep TJ Sport 4.0
Kilby Steering Skid, Skid Row Engine Skid
JKS Quicker Disconnects, 1" PA Body Lift, 2" BDS Spring Lift
33" BFG KM2's on AR Baja Wheels