[44net] Openwrt x86

Hi! I have a dual Nic micro atx MB that I use as my main router on my 120/20 MB residential connection. I was wondering if it would be possible to have a 3rd nic (pcie) that could be use as the apmrnet gateway to hamprnet for my allocation. I dont want to have my local home net available on 44 net but if I need to hook up my segment to the internet I want it to be available. I am not bad on linux, but I am not a network engineer. Been playing with wds ap/station captive portal and modding routers. but this is just over my knowledge base. Anyone willing to help? Thanks Pierre VE2PF