NO NO NO NO NNO NO NO GLUEING WTF ARE U THINKING???!?!?!1//what type of seats do you have?
if they have carpetting on the back then you should be able to remopve the factory seat cover if needed.
what you should do to have a solid mount to mount the amp on. buy some 1/4" wood.. any type. get the cheapest **** if you want.
remove the seat cover and measure an area where you can place a board inbetween the back of the seats foam and the seat cover. cut it to size, place a wood panel in between the foam and seat cover, then screw the amp onto the cover into the wood. problem solved.