Dishwasher drawers are a thing of beauty! However, as of yet, IKEA does not have a cabinet sized for the Fisher Paykel drawers. The following is an account of one person's installation of a single Fisher Paykel Dishwasher Drawer utilizing a combination of IKEA Akurum cabinets and a Mills Pride drawer.
As the standard 24" cabinet is too small (you need 24" INSIDE space, not total), I cut down a larger cabinet (circular saw with Diamond blade) to fit and redrilled the holes carefully, then reinforced the cabinet with corner brackets. You just leave the cabinet the same size and use filler boards on the inside to "close up" the space. I would NOT recommend just putting in a shelf in between, as a cabinet there would give you reinforced sides for the weight plus you must enclose/protect the cavity against moisture.
For the shelf to support it, you simply use a small strip of wood screwed into the inside of the cabinet to support the shelf and evenly distribute the weight of the DD INSTEAD of pegs (we used four screws on each side). We utilized the ledger boards that come with the base cabinets for the shelf support or you can use 1x2s.
