[Babul]

you could attach an invisible (or small) platform to the rope, and place the player on the platform. when the platform moves down slowly, the player will be able to crouch/shoot. the AttachObjectToObject's last parameter "SyncRotation" set to 0, will force the platform to be orthogonal to the ground, the players wont slip off. just a suggestion btw, didnt script/test that..