The file /etc/rc.config.d/netconf is there merely for your convenience to have interfaces brought-up at "boot."
You can run the ifconfig command by hand at any time (well, after networking has been initialized :) which means you can script it too.
What sort of large network simulator are you creating? I take it you want to simulate the presence of a large number of systems on the network?
there is no rest for the wicked yet the virtuous have no pillows