Replacing Better-Bilt window latches

I need to replace Better-Bilt window latches (26-295)on top of sash. There are only two slots on each corner without any holes or screw to make them fast onto the sash top. I think I just need place the latch on the mounting surface, with theri two hooks aligmed with the slots on top of sash, and then press the latch donw very hard until hearing a "click" sound. So as to press the two hooks into the mounting slots and the latch will be fixed firmly. I do not know if this procedure is correct. I am afeaid that such operation might very likely break the two plastic hooks on the bottom of the latch. Another question is how to remove the old latches. It is plastic and no screws. The only way I can imagin is just destroy it by force, because you do not need it any more and easy to break and remove them. But also I am afraid I am wrong. Please give me correct instructions about how to remove and install a new Better-Bilt window latch (26-295)onto window sash. Thanks!