Using a gamepad’s analog stick to control throttle?

[DarHan]

My flight stick unfortunately broke a few months ago and I’ve used a PS4 gamepad borrowed from my brother to play XWA, using one of the analog triggers a the throttle axis. But now the PS4 gamepad has become unavailable and all I have left is a generic gamepad to play with. However, using one of the analog sticks to control throttle is annoying since, by default, the stick sets the throttle at50% unless explicitly pushed forward or backward. Anyone know how I can turn it into a relative axis (i.e. push to increase, pull to decrease, leave untouched to keep current value) rather than an absolute axis (i.e. push to increase, pull to decrease, leave untouched to set throttle at 50%)?