Tour de France 2009

I think he means how do they inject it 'during the stage' although I suspect thats not what you meant.
Also its worth noting that you could buy EPO legally without pescription (in Switzerland at least) so it wasn't exactly hard to get hold of.

It's not injected while on the bike, it's injected 2 days before a key stage since the day after injection is supposed to be poor with the riders feeling flat after the infusion.