Application Port Routing

Hi guys,

Please can someone help with some guidance.
Scenario:
I have 2 PPPoE accounts breaking out via the same WAN interface, one is a capped account and another is an uncapped account.
PPPoE1(Uncapped account) → ether1-Wan
PPPoE2(Capped Account) → ether1-Wan

I would like to route all application specific traffic, both upload and download, from port 5555 via the uncapped PPPoE Account(PPPoE1). All other traffic I want to route via the capped PPPoE(PPPoE2).

Any help would be appreciated.