I installed a small MW in our BF years ago. Under the cabinets. I did a bit of wood work inside the cabinet floor for attaching. I removed the lid of the MW and attached it to the cabinet, then lifted the MW up and attached it with screws.
I prefer the old mechanical timer/control settings v/s the electronic type. Less to go wrong. The electronic types are quite susceptible to shore power surges from generators etc.
That said I wish the MW manufacturers would start putting inverter type power supplies in the small MW's. They weigh about 20 lbs less.
Wife loves this one even though it is only 750watts.
Jim