ASUS can put this under "stupid user error"
OK - for people as dumb as me, follow these instructions:
1.)Goto asus site, search for WL-HDD.
2.)Goto downloads
3.)Select BIOS
4.)Download update
5.)Open configuration page on router
6.)Goto firmware section
7.)Try and upload still zipped firmware.
8) Goto 1 as many times as you like, it ain't going to upload.
Or
Do steps 1 to 6
7.) Unzip firmware
8.) Upload
9.) Wait.
D'oh.