> Or import a low resolution human body
> and then, with MoI, create a perfect jetpack.

For a low resolution mesh, you could use a workflow of import the low res mesh into Rhino, convert it to a NURBS model using Rhino's MeshToNurb command, which will convert it to a faceted NURBS model with a trimmed plane for each original polygon face. That faceted NURBS model can then be imported into MoI.

That can work for low polygon models but it isn't very good for higher polygon counts because the way NURBS models are structured they don't deal well with a huge number of little triangle facets instead of having larger smooth surface patches.
See here for some additional explanation:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4247.76

- Michael