You should be able to that via "DragToolbarButtonFromCommandID"
These codes will add a new macro button to the macro toolbar but I've no idea as how to add/edit properties for that i.e. setting the macro path, macro button image, etc.
Dim swApp As SldWorks.SldWorks
Set swApp = Application.SldWorks
swApp.DragToolbarButtonFromCommandID swCommands_NewMacroButton, swMacroToolbar, 0
Instead I would suggest you to use the registry file option which is quite simple and easy to use.