[jpstewart]

IRIX package naming conventions can be a little confusing if you're not used to them.  The name 'eoe.sw.ipv6' indicates that the ipv6 subsystem is part of eoe.sw, which is on the Foundation 1 disk.  There won't be a separate eoe.sw.ipv6 file.  You'll have to open eoe.sw in inst or swmgr and then manually select the ipv6 subsystem from it. 

Note that there will likely be an eoe.sw overlay, too, on the Overlays 1 disk.  You'll probably need both the base and the overlay.