1. Set up base station as desired. Note that, for repeating to work on these routers, one must use WEP and a fixed 2.4GHz channel. Also, the only data rate is 54Mbps, and it'll run at half-duplex on account of repeating. So long as it's faster than my connection to the 'net (which it is, but not by much) I'm content.
2. Configure base station as base station of wireless repeating. This step amounts to adding the repeater's MAC address to the base station's configuration, and checking a box on the admin page.
3. Configure repeater on same channel (and with same WEP information) but use a temporary SSID. "Apply" and the router will reboot.
4. Connect to the repeated on a wired network. Configure it as a repeater, set the MAC address of the base station and choose an IP address on which the repeater will live. The verbage on the Netgear setup page was pretty unclear -- you're entering the MAC address of the base station but making up an IP address for the repeater. Choose some IP address that the base station is unlikely to give out as part of its DHCP. (One can probably block out that address but I didn't bother -- I'll never have so many devices on my network that it'll confict.) "Apply" and the router will reboot.
5. Change the repeater's SSID to match the base station's. "Apply" and the router will reboot.
6. If all is well, at this point if you try signing in at routerlogin.net (Netgear's URL for all local router logins) you'll reach the base station -- even though you're on the wired network on the repeater. That's what you want. You can confirm all is well by visiting the IP address you used earlier -- you should be at the repeater's admin page.
And that's the story of how we got a second wireless router. The End.