Barcon was a trademarked name used by Suntour for shifters that mounted in the end of drop handle bars. Most people use the the term for any brand of shifter that plugs into the end of drop bars. The only difference between barcons and down tube shifters is the bar end plugs the shifters screw into-- if you have a those plugs, you can use the regular down tube shifters!
It's possible to use barcon shifters with ANY bike--- but it might take some thought and some extra parts. And it doesn't take a lot of skill to do this yourself.