Unwedge requires that the support start within the tunnel. So, modeling spiles with the support elements in Unwedge is not possible.
One thing that may work is to increase the cohesion along the joints according to the number of spiles intersecting a wedge. For example, if a spile intersects a plane, increase its cohesion by
sigs is the shear strength of the steel,
As is the cross-sectional area of the spile and
Ap is the area of the joint plane.