SS to FG

Best bet is getting a bike shop to put it on and tighten it. You don't want a loose sprocket stripping the threads on your hub.

They shoulf do it for nothing if you buy the sporcket and lockring from them.

I agree with this.

I own a Charge Plug which I have ridden in both SS and FG "mode".

If you buy a chainwhip, make sure you get the right type to fit your rear cog (I made this mistake). Also some chainwhips have a lockring tool included.