Decide where you want to put your manhole. Check there is room between the studs for the panel. Measure up your panel then use your pencil to mark the centre point on the ceiling. Now measure out and mark the edges of the panel on your ceiling.
Check in the roof to make sure there are no electrical wires that you could accidently cut into. Use the keyhole saw to cut a small hole at the centre point. Now use the reciprocating saw to cut around the marked edges.
Insert your manhole frame into the hole. Make sure it is nice and snug. Then drill a pilot hole through the frame into the timber roof beams. Use screws to secure the frame in place. Finish off by inserting the cover panel.