[oe] How to modify /etc/network/interfaces file in a OE recipe

[Elvis Dowson]

Hi,
       Would someone be able to help me with modifying an omap3-console-image recipe, such that in the final image, the /etc/network/interfaces file gets edited as follows

#auto eth0				<- remove # sign ( auto eth0 )
#iface eth0 inet dhcp		<- remove # sign ( iface eth0 inet dhcp )
#iface eth1 inet dhcp

I am using a Gumstix Overo + Chestnut43 expansion board, which has an inbuilt wired ethernet interface. I have to make this modification manually, to enable this interface each time. However, if I can modify the OE recipe somehow to do this it would be great. I know it can be done, but I don't know where to start and which file to modify. 

Elvis Dowson