Step 4: Remove the old parts.
The original regulator and rectifier are two seperate units bolted to the frame under the saddle.
So remove the saddle and have a look for two silver boxes with cooling fins on joined together by a short length of wire. Helpfully they have the words "Regulator" and "Rectifier" respectively embossed on them.
Undo the snap connector attaching the wiring loom to the rectifier. Undo the two bolts and they should lift off.