do you have 2 pairs of infinities or just one pair....? Either way you dont have anything special to do with the RCA's Front out, and Rear out both go into the amps related inputs.
What I'd do.... if you just have the infinities in front (one pair), run them to the front channels of the amp 4 ohms a side.... Then wire the subs series each, to get 8 ohms per sub, parallel the pair to the rear channels, or just leave the subs 2 ohms a piece and run each independently to the rear channels.
Just run the RCA's normally.... front into the front channel inputs usually 1 and 2, and the rear RCA's into the rear inputs 3, and 4.
Or.... If you just want to run the infinities off the HU... and your amp supports 2 ohm loads bridged, just run a sub per bridged pair of channels, like 1 sub bridged on pos ch 1 and neg on ch 2, and the other the same on the rear channels...