Hate to be the bear of bad news!
Just installed it on my vB3.5 board and it seems to not be working.
Firefox Browser
Instead it's working just like the quote button when clicked. No text get copied to QR, it opens a new reply window as a quote button would and it quotes the whole msg.
Internet Explore Browser
Seems to work t'll a certain point.. It copies the highlight text but it does not unable the QuickReply box and when I un-highlight the text and click on "QR" button it directs me to a REPLY page and it quotes the whole post.
Hence
Not sure if it works when you have vB option Quick Reply to "Yes - Click Not Required"; I have it set as "Yes - Click Required".
Seems like a promissing hack ported here by you, hope you work out the bugs!
Good Luck