You essentially want to wrap ifconfig with sudo or a sticky bit. I think this would be pretty easy in a shell script.

#!/bin/sh
sudo /etc/init.d/network stop
sudo ifconfig . . .
sudo /etc/init.d/network start
[download]

I don't have debian in front of me, but I'm pretty sure that that is the location of the network start/stop script. At any rate you can take some params going into the script if you want, but I'm not sure what Template::Toolkit will really buy you in this case.