How can I calculate the inverse kinematics of a system using Simmechanics?

I want to simulate a kinematic model of the human spine using the Simmechanics Toolbox.

I modeled the spine using DH parameters, meaning I connected rigid bodies with spherical joints, each represented via three revolute joints. I reduced the DoF of the system to 3 and now want to set a desired pose of the end-effektor and let Simmechanics calculate the three unknown angles. Since it is not possible to actuate bodies with a given position, the only way I see to solve the problem is, that I need to calculate the values for the joints by solving the nonlinear equationssystem I obtain from the homogeneous transformations. But when I do this, I do not need the simmechanics model at all.

Is there a possiblity to let Simmechanics calculate the inverse kinematics for a given point of the end-effektor?