Because Australia has no guide data, there has been a lot of work done on www.xpmediacenter.com.au
about this topic. You may want to check there for more information, and check out the programs already available to do this kind of work. Bladerunner, EPGStream and it's friends are all interesting packages that add guide data.
100 downloads a day for Yougle Vista - goin' allright!
Check out http://www.thedigitallifestyle.com/cs/Blogs/developer/default.aspx and http://www.push-a-button.com.au/products/mce