Installing Customea pieces should be as easy as adding the hinges and popping them onto your cabinets.
Follow your IKEA installation instructions the same way as you would with IKEA doors/ drawer fronts.
Side panels may require some cutting (if you have uneven walls or floors or need a shorter length) prior to attaching with screws (this should be done from the inside of the cabinet with short screws so you do not pierce through the cover panel as well).