Regardless of the processor being used, once the IPL code is started, it has to load the image in a manner that meets the requirements of the microkernel as described above. The IPL code may also have to support a backup way of loading the image (e.g. an .altboot in the case of a hard/floppy boot). This may also have to be an automatic fallback in the case of a corrupted image.
Note, however, that the amount of work your IPL code has to do really depends on the location of the image; there may be only a small amount of work for the IPL or there may be a lot.
Let's look again at the two classifications of image sources.