Turn-off/fool etagging?

Is there anyway to turn-off or fool etagging so that it will re-render
the page and return 200 rather than 304?

I'm writing a Facebook app and logging in causes Facebook to
immediately hit the homepage again but I'm returning 304 rather than
200 and the home page content again.

I've tried a hidden <div> with the current time trying to force
something new onto the page but this doesn't seem to help.

Any pointers would be appreciated.

Thanks-- Mike