What needs to be done to support network interfaces in userland?

I am mostly curious about this for developing and testing without 
rebooting kernels.

If this has been discussed before, please point me to it.

By the way, I have a USB-based internal wireless interface I want 
supported:

	port 6 addr 3: high speed, power 500 mA, config 1, 
	RTL8187B_WLAN_Adapter(0x8197), Realtek(0x0bda), rev 2.00, serial 
	00e04c000001