I notice these instructions don't require removing HD & memory, which would seem to confirm it's not necessary to do so for a Toshiba Satelite L300, which is virtually the same as a C660 apart from not having a separate number pad.

Incidentally these instructions can also be for replacing a C650 keyboard as I have just done so successfuly thanks for the very clear instructions, so full marks!

Removing the battery as a precaution against short circuits while disconnecting/reconnecting the keyboard makes sense but I fail to understand why you say it's necessary to remove the HD & Memory as well; please expalin?