Multiple output routes

[O-Zone <liste@zerozone.it>]

Hi all,
i want to route traffico for a specific subnet to routeA while default route 
for my linuxbox is routeB. Here's the diagram:

(internet)--[Router A]---+
                                    |
                                [Linux BOX]----(Subnet 10.0.0.x)
                                    |
(internet)--[Router B]---+

RouterA and RouterB have the same subnet (i.e. RouterA lan is 192.168.0.1 and 
RouterB has 192.168.0.2) and LinuxBox have ONLY ONE externat iface like 
192.168.0.3. While i use LinuxBOX i wanna go "out" trought 192.168.0.1 but 
PC's MASQ'ed in Subnet 10.0.0.x must go out throug 192.168.0.2. 

Can someone point me in the right direction ?

Thanks ! Oz

-- 
------
O-Zone ! www.zerozone.it