[Feanor]

I want to hold down a button the left button on my touch pad so I can scroll without keeping my figer down on the physical button on my laptop,

[ciocan]

I dont think this is possible. If you block that button other things in windows will stop working or you will not be able to do anything.
What you may do is to try to play with the setting from the StickyKeys. Press 5 times shift button for settings.
I dont know if will work what you are try to do.