I tested it now and it works fine for me.
I installed the current version of Chrome (Version 24.0.1312.52 m) and then the Tampermonkey extension, which is apperently like Greasemonkey for Firefox. It wasn't possible to install the script directly because of the "security" settings of Chrome.
To copy code to the clipboard, one has to select it, which is especially cumbersome if one has to scroll up or down while selecting.
I "found" a usefull script on https://stackapps.com/questions , which exactly provides a "Select" button, if the mouse is on a code field: https://stackapps.com/questions/2553/select-code-block-buttons-script