So, I assume you want to copy from the OSX QuickLook directly.
Guess what, it's just 1 step to copying madness.
1) Fire up your Terminal and run the following in it (SINGLE LINE).
defaults write com.apple.finder QLEnableTextSelection -bool true; killall Finder
Now, go and copy those words.
[ Optional : I hope you've already enabled QuickLook for all plain text files by now. If not, do that here http://coderwall.com/p/dlithw ]
Maybe you'd like to follow me on twitter, I don't make a lot of noise.