Chrome support is default... it will work, you don't have to do anything.
As far as in-game support.. either use 'Simulate' or use the Gamepad events themselves.
start with this..
create a textbox..
add an event for the Gamepad.
use Gamepad 0 any button pressed
for the action use set text to "button pressed:" & Gamepad.LastButton(0)
0 is your first controller
1 is your second controller etc...
this will give you the value of what each of your button presses produce..
the analog sticks also have an axis parameter which you can check as well..