General :: Using Ifconfig Without Using 'ethX'

I'm a relatively inexperienced with Linux, coming from a Windows background, and I struggling to solve a troublesome issue attempting to set a static ip address to a Live Debian USB Key. I know it is possible to utilise the 'ifconfig' function to set a static ip address and use 'route' to set the gateway, e.g.

ifconfig eth0 10.0.0.40 up
route add default gw 10.0.0.130 eth0

..however in both cases I need to explicitly set the 'eth0' to point at the appropriate adapter. However, this is where my problem is...

I'm creating a persistent USB key using the Debian Live CD, I'm going to create an image and then duplicate that image to a load of other USB keys. Again, not a problem as such but there are cases where I need to specify a static IP address and gateway rather than using DCHP.

And here's where problem raises its head.

Because I've created the key on another machine it has allocated 'eth0' to a specific MAC Address (assigned in /etc/udev/70-persistent-net.rules) but when I place it into machine with a different network adapter it is assigning to 'eth1' (and this increments up).

a) call 'ifconfig' and 'route' without having to identify the adapter or

b) change the script that is creating '/etc/udev/70-persistent-net.rules' so it overwrites the 'eth0' entry with the only applicavle network adapter for the current hardware.