Solidworks can import STL Stereolithography files (used for 3D printing), so with it you should also be able to transform / convert it to SolidWorks' SLDPRT format. If you do not have access to Solidworks, you will have to rely on some 3rd party solutions or 3D model / CAD converters.
Open STL file Open SLDPRT fileA set of 3D modeling tools
A CAD visualizaton, analyzation and translating system