Ignore scroll when modifier is used

[mattbatt]

Main problem: I don't have the right lingo to search for the answer.
What I'm trying to accomplish: If I tap my mouse's Button EXTRA key it does KEY_HOME, If i hold the Button EXTRA + Scroll up and Scroll down it will turn the volume up and down.
The Problem The Volume change works however the scroll wheel is also scrolling the page up and down in the back ground while changing the volume and it does the KEY_HOME thing in thing in the background too. Which wouldn't be a big deal except that KEY_HOME restarts YouTube videos from the beginning.

Thank you.