Cable over Roller or Pulley
You can model roller support for the cable, such that the undeformed length of the cable between two adjacent support points remains the same (is independent of applied loads), but the roller moves depending on the applied loads. It is however not possible to directly model sliding or rolling of the cable over the pulley, such that the undeformed length of the cable between two cables changes when loads are applied.
Point Load To Cables
To apply point load to cables, you need to model the cable using multiple segments such that a point object is present at the location where you want to apply the point load. Similarly, if you want to apply UDL to a portion of the cable it should be discretized such that the portion of the cable that has the UDL is a segment in itself.
Cable