If you are willing to do the brute force yourself I'd try:
http://translate.google.com/translat...lr%3D%26sa%3DN
This is the page I have bookmarked, and it brings up a page not found, but you can navigate from it. And get all the information you need. Or jsut search for memoire-du-cyclisme in Google and use the translate option (unless you speak French).
The site is excellent. A few years ago I posed the question here "Which riders won the TDF on their first Entry"? Many here came up with wrong answers because they foolishly trusted the official TFD site, which it turns otu only listed finishers and several riders in hte early years won the first time they finished (but not the first time they started).
I'll bet the brute force will work for most participants without a podium! I'd first make a list of countries that had a Podium placement, then check the years with National Teams. That will give you ther candidates. I believe one of the French posetions in Africa had a team at least once. Oh and from this site:
http://homepage.ntlworld.com/veloarc...aces/index.htm
I was able to find out that the best English finisher up to 2001 was Robert Millar in 1984. I checked and no podiums since then. My money is on England!