You don't even need to go to the chumbalum website.
The importer is already in the program.
Go to File>Import>Autodesk 3DS
its worked for me before.
For joints, click the model tab (left side of screen) and then hit the joint tool. Now, when you click in any of the windows (not the 3D one) it will 'spawn' a joint. Just remember to deselect any previous joints before making a new one.
I assume you know what names to give all the joints.