I don't know how Mark did it, but we drilled the 2 1/2" hole for the vent can first. then we drill a smaller hole next to it large enough for a grommet that fit the hose snugly. Then file the remaining metal between the two holes to form a "keyhole". Then the order of assembly is shock canister through the big hole in the floor, slide the grommet and hose into the small end of the keyhole, and then install the vent can.
Here is a shot from underneath. The hose looks really close to the exhaust, it is not. The other plus side to doing it this way, is you run the shocks inverted so the rebound adjustment is easily accessible. Especially important with the JRi shocks.
