ASM codes can be put into a file. WiiRD-type codes can't be done so easily unless you also put the code handler into the ISO.
ASM codes essentially consist of two things; first, a RAM write into empty space of replacement code to be run in addition to the game's normal code. Secondly, a RAM 'over'write to add a branch to this replacement code at some point (usually a code-appropriate one) in the game's actual code. It is presumed that it is fairly simple for a piece of RAM-write code to be written into the game's true source code.
WiiRD-type codes, though, rely on things which are not recognised by the game. When you write a WiiRD code, you're not telling the game to do something, but rather telling the code handler (which Gecko OS initialized) to do something. Run an Iso, though, and there's no code handler. That said, it seems likely that every WiiRD code -can- be converted into an ASM code, with variable degrees of elegance. Most notable it can be a hassle to do this kind of thing with codes such as changing the stage speed with a button press, because by default the game's code which handles this kind of thing doesn't also have much data on which buttons are being pressed, and ASM uses relative coordinates for addresses instead of absolute ones.