One option that works for me is imwheel. It is in the standard repositories.
In $HOME/.imwheelrc one can put something like:
"^.*Chrome.*$"
None, Up, Button4, 6
None, Down, Button5, 6
"^.*Firefox.*$"
None, Up, Button4, 7
None, Down, Button5, 7
".*"
Control_L, Up, Control_L|Button4
Control_L, Down, Control_L|Button5
Control_R, Up, Control_R|Button4
Control_R, Down, Control_R|Button5
The values 6 and 7 refer to increased scroll speed.