Dual ISP but...

Good day to all,

I just want to ask what set up should be for my ccr1009 that is configured for Dual ISP,

Situation:
eth1 (100mbps) and eth2 (50mbps) = ISP
eth3-eth5 = using the dual ISP set up

but for eth6 I want to configure it for only 1 ISP (from eth2 (50mbps)

what is the configuration to do?
can you give some step by step procedure,

thank you,