single user mode with wireless keyboard?

Here's one: I've brought my iMac and my wireless keyboard with me on a weeklong trip. My install DVDs and non-wireless keyboard are at home, but iMac needs a disk repair according to disk utility.

In the past when I've needed to fsck my Mac til she's satisfied (ha) I've simply plugged in my normal USB keyboard and did command-S on restart, or used the install discs

Here I can't do either.

Any ideas?

(The keyboard is a Microsoft Wireless Comfort Keyboard, not an Apple one, if that makes any difference)