Loadbalancing Multiple DSL Lines

Hi all,

I'm pretty sure this won't work but I have to ask anyway. Is there a way to
loadbalance multiple DSL Lines (or even a DSL Line with a cablemodem Line)
behind a single m0n0wall instance running on an Alix board?
The problem is that my users need quite some bandwidth, which can only be
satisfied by a cable connection, but I hate that cable provider since
instead of the 99.9% uptime guaranteed, they had a rhough 3 weeks downtime
last year, therefore the DSL as backup line.

Even more importantly: the cable provider does not allow static IP
assignments which is critical for us since we have to provide some services
(Mail, HTTP, DNS, ...) to the outside world.

So services use the DSL line, users use the cable line if available, DSL
otherwise.

Is there a way to do that?

Regards,
Chris