One small piece of wood - file groove on top.
One out-of-date fridge magnet - chop up and superglue suitable piece to wood.
Plonk piece of wood on OTA up against finderscope dovetail bracket, or against edge of focusser.
Calibration - take laser out of top pocket (where it is kept warm so beam doesn't fade) and place on groove. Push wood against finderscope or focusser straight-edge. Check beam clears end of scope. If not, get bigger piece of wood. Look through low power eyepiece and make small adjustments until end of beam is close to centred in eyepiece. If necessary, can shave/file the wood edge and the groove - but I find with the magnet, once I have the groove right, I just have to slide it to the right position and it holds the position for the night if I'm careful placing the laser on and removing from the wood.
That done - operate. Place laser in place, push button, move scope until the end of beam is at desired location. Laser off and back into pocket. Observe object.
Required - steel OTA