Try as I may I cant find what controls this, neither in the tech or terrain xml files. What would I have to change so that the great peoples of my mod can get wasted much earlier in history?

In your Assets/XML/UNits folder. Find Civ4BuildInfos XML file and then search for winery. Change tech prereq.

Remember to back up your original files as well. ;)

Yeah. Or make this a mod. In that case you need one file and just those folders.

Tested it out and it worked like a charm! Thanks guys!