It is 'possible', but you would need to rewire most of the car - not only is the Pektron Systems Control Unit in a different place from both the 5as and the Multi Function Unit it replaces (so the wiring to the various electrical components wont be routed/finish in the same place), but the way some systems are operated is different too. On top of that, the later facelift centre console switches have different connectors, and even where connectors appear the same or similar (as on the Pektron equipped late pre facelift cars), you sometimes find the way they are wired is different.
Why do you want to replace the SCU? The problems that do occur are well documented, and for the most part reasonably cheap and easy to repair; many of which are covered in this thread. Technozen can repair nearly all SCU faults short of a completely fried unit.