Phone used: This was done on a EVO 3D with 2.3.4.
This kinda assumes that you have installed the market from a APK that just landed in your lap (somehow).
But, you want know to try to let google update it. And want to FORCE update it. This works at least for me.
Settings > Applications > Manage Applications >All > there you find Market.
First you Clear data and Clear cache then you click on Uninstall updates, just follow the guide. And Now you should be back at the OLD version
Now you start Market and accept the ToS, it opens as the old one. Play around a little in it, at least a couple of minutes. Download something, and then exit from it via the Back-button. And wait a little and then start it again. This time it should start a little slower then normal and showing a Accept or Decline buttons. And you have forced a new version onto your phone! This way i got 3.3.11 since 3.3.12 doesn’t to be live in my parts of the world yet. If it doesn’t work the first time, just try again.