advanced routing packets from localhost

[ESGLinux]

Hi all,

I have posted several questions in this list about advanced routing with
iproute2 to route the traffic as I want throug 2 different ADSL lines.

I use packet marks to route them through  the selected gateway. All works
fine, but I have a problem that I can't resolve.

I need to route the traffic originated on the server I use as
firewall/router but I don´t see how to do it because the routing decision is
made before the firewall does anything.
>From this web:

http://www.linuxtopia.org/Linux_Firewall_iptables/c951.html

*Table 6-2. Source local host (our own machine)*
StepTableChainComment1  Local process/application (i.e., server/client
program)2  Routing decision. What source address to use, what outgoing
interface to use, and other necessary information that needs to be gathered.

so all the traffic generated in the machine goes to the default gateway and
I cant´t control it,

Any one knows how to solve this route problem?

thanks in advance

ESG