I am sorry but that's not possible. Moji uses offline versions of
dictionaries in edict format. As far as I can tell Eijiro does not use
edict format.
Edict is not a free dictionary. Thus, even if we got a copy of Eijiro
and extracted an edict format dictionary we would not be allowed to
redistribute the moji dictionary for free.
You can ask the makers of Eijiro whether they are willing to create a
package for moji and sell it on their website. I could give them some
assistance how to built the XPI package and how to use the edict format.
As moji is open to operate with any dictionary package which follows the
necessary structure and conventions moji is open to be extended by
commercial dictionaries in this way.
Cheers,
Gerald