In HSMWorks as in SolidWorks - the units that values are entered and shown in do not depend on the internal representation of parameters, geometry and toolpaths.
As such, it is possible to change the units on the fly without any conversion of parameters, geometry or toolpath.
The display units can be changed by changing the unit of the SolidWorks document.
1. Open the Tools menu
2. Choose Options
3. Go to the Document Properties tab
4. Choose Units
5. Select the Unit System and individual units you wish to use