Hi Matt,

I have learned a lot about cables under tension from jj77 who is knowledgeable about this, and may have something to add.

A command called INISTATE creates an initial state of stress (or strain) in an element at the beginning of the solution. Look that up in the ANSYS Help system.

Attached is a model of a long cable that has an initial stress applied so you can see how it is done.

Since you want a force, you will have to calculate the stress that force will create in the cable. 

For a cable, Stress = Tension Force / Cross-sectional Area.

Pay attention to the units once you start using Command Objects.