It would depend on the orientation of the slide but in a worst case scenario, with the slide facing horizontally, it is able to handle 2lbs quite easily. Keep in mind that the drive mechanism (servo, motor, etc.) will need to have adequate torque to move the load.
The motor or servo (whichever you choose to mount on the slide to drive it) will wind the synthetic cable in and allow the slide to extend. When the direction of the motor or servo is reversed, it will wind the string back in and the latex surgical tubing will allow it to retract.
