Your strut needs not run along the X, Y or Z axis. To identify your own restraint "vector", follow the vector name (typically X) with the three components that point in the direction of the restraint action. For example, to define a strut working in the horizontal (X-Z) plane and off the X axis by +30 degrees about Y simply enter as "X(0.866,0,-0.5)" or "X(1.73,0,-1)".

If you want the restraint to work only in tension, add a sign in from of the X as in "+X(0.866,0,-0.5)" or "-X(0.866,0,-0.5)". It's up to you to use the proper + or the -. The vector you are defining is the direction of unrestrained motion. (As in +Y means the pipe is free to move in the +Y direction.) I know it sounds backwards. But check the results to be sure it's working the way you want it.

Using this definition it should be evident that "+X(0.866,0,-0.5)" is the same as "-X(-0.866,0,0.5)".