You can use either the older version of the tracking code (urchin.js) or the newer version (ga.js). Once you've installed the tracking code and have elected to share your data, the Benchmarking Service accrues data from all the sites and pages on which you've placed the Google Analytics tracking code.
Note that once you've enabled benchmarking for your account, it can take up to two weeks for the data to appear in the Benchmarking report.