Where to change mouse settings (for scroll mouse)?

[kettlewell]

This is on a recent install of LXDE from disk, with all Yum updates applied.

I can't seem to find where I need to tell LXDE that I have a 3 button scroll mouse.

I thought I needed to edit my Xorg.conf, but there's no such critter ??!?

lxinput gives my config options for a mouse speed, etc, but not to tell it what mouse to use....

What do I need to do to get my scrolling to work?

I think that it was working before I did a Yum update (but I'm not 100%)

Any help would be appreciated.

Thanks

Matt