Multiple ISP routing by port

[jmaps-fbsdnet at fireburns.net]

I've read through what I could find in this list and also in the top 50 results on google... I can't find anything that'll actually make this work.

My DSL ISP is too far away to give me anything faster than 1.5mbps down. In despiration I signed up for comcast to use for bulk traffic.

Thus, I want to route critical traffic (22, 25, 53, (maybe) 80, 443) through the DSL provider and the rest through cable.

I really feel like this should be possible with PF with something like:

nat on $dsl_if from ($int_if:network) to any port $dslports -> ($dsl_if)
nat on $cbl_if from ($int_if:network) to any -> ($cbl_if)

or

pass in quick on $int_if route-to { ($dsl_if $dsl_gw) } proto { tcp udp } from ($int_if:network) to any port $dslports

Neither (or both) seem to do it. All traffic ends up getting routed through whichever ISP i have set as the default route.

Now, I hear i can go over to linux and just configure both default routes at the same time (trivial with iproute2). But I'd rather avoid that if at all possible.

Is there some trick I'm missing? Does quagga (bgpd) allow for this kind of routing scheme?

Thanks,
Jesse