I would like to update my remote CPU MKI to the latest software. Is it possible to do it with a Mac?
No, it is unfortunately not possible with Mac using either Mac OS X 10.7, 10.8 or 10.9.
It is still possible with to do it on OSX 10.6 but we recommend that you use a PC to do that update.
Please follow instructions described in this FAQ:
System 6000: Running original (black) ICON remote / ICON editor with MKII mainframe