I've done both.
Glovebox
just use your fingers (no tools required) and prise the light out and down out of the aperture. Disconnect the cable (making sure it doesn't disappear back inside). With the light out, use a tiny flat screwdriver and pass it up the gap between the plastic lens and the metal heat shield cage that surrounds it at each of the 4 corners. You will see 4 small notches in each corner of the heat shield, just lever these out very slightly and the heat shield slides off upwards. With the shield off, the bulb then becomes easily accessible.
Boot
From memory, this is even easier as there's no heat shield covering the whole of the back. Just lever the light out of it's housing (there is a small screwdriver cut out at the end you need to remove first). Once the unit is out and unclipped from the harness, just pop the festoon bulb and and replace with the LED version.
On both just remember that LED's unlike conventional filament bulbs, only work one way round (polarity). So if the light doesn't illuminate at first, just pop the bulb round 180° and try again.