Yes, you can use OIToPWM() for direct drive or use GetOIAInput() with SetPWM() and make adjustments.
Code:
void OIToPWM(port, axis, pwm, direction)
port - the joystick's port on the OI
pwm - pwm output port number
axis - 1 = x, 2 = y, 3 = wheel, 4 = aux
direction - 0 = normal, 1 = invert
unsigned char GetOIAInput(port, axis)
port - the joystick's port on the OI
axis - 1 = x, 2 = y, 3 = wheel, 4 = aux
void SetPWM(pwm, value)
pwm - pwm output port number
value - the value to set it at