Can't connect with more than one interface simultanely nm

[n0t]

Hi all,
i am trying to configure networkmanager with gentoo and gnome.
So i got a problem, pratically i have 2 netdevices eth0 and wlan0
so i need that @ startup
eth0 should have 192.168.0.3 ip
and wlan0 192.168.1.3

but networkmanager make me choose just one interface to be connected
if i select throught nm-applet a wireless network , the eth0 wired network goes down
otherwise if i select eth0 wired network , wlan0 wireless goes down .. X_x

i'll be nice if you decide to help me to resolv this situation
thanks in advance and sorry for probably english language error , this isn't my mother language