Install
Drag and Drop the XFormer .mzp installer onto your 3ds Max viewport or run it via Menu|MAXScript|Run Script... and click Install.
MacroScript
You can assign a "Hotkey" or a Menu Item to open XFormer.
To access it go to Customize->Customize User Interface... in 3ds Max menu bar, and under "Category" select XFormer as shown in the image bellow.
Uninstall
To uninstall XFormer, simply Drag and Drop the XFormer .mzp installer onto your 3ds Max viewport or run it via Menu|MAXScript|Run Script... and click Uninstall.