Not sure if this is useful but figured I'd share anyway.
Output of the 'file' command in linux:
otheros.bld: gzip compressed data, was "exoboot", from Unix, last modified: Mon Nov 27 01:23:01 2006
Change otheros.bld to otheros.gzip and do 'gzip -d otheros.gzip' and you get jus otheros file. The 'file' command now labels this file as just data. If you open it in a hex editor now, you will be able to see all the strings as plain text. A significant part of the beginning of the file consist of small chunks of data and then one large area, then the strings.
I couldn't get IDA to give me any ppc instructions so using a disassembler wasn't useful at all. I know the kboot source is openly available so I'm not sure of any usefullness of this right now. Some of the strings might provide a little insight on wat this paticular file does. When I looked up exoboot, all I got was information on a Dream Cast iso loader of some sort. Not exactly sure how that pertains to this file. Maybe going through the hex code will provide something useful.