I believe that is one of the open issues for Marc4j.   I do not know how 
to push a jar or a new version of a jar to a Maven repo.
I believe Bill Dueber was looking into this just last month when he 
wrote the following to the Solrmarc list:

    I'm trying to get marc4j into maven central, and I don't know who
    owns the domain. If it's one of us, then we can use it. If not,
    well, I'm not sure what we do (except maybe use the github location?)

    -- 
    Bill Dueber
    Library Systems Programmer
    University of Michigan Library

The last release I did was to merely create the jar in the releases 
sub-directory, and reference it in the README.textile file. That 
emulates the way the releases had been done from the tigris.org site, 
but its not the right way to do a release.

-Bob Haschart

On 11/13/2013 4:43 PM, Jonathan Rochkind wrote:
> I am a committer, but I have no idea how to do a marc4j release.
>
> There are some fixes in master repo for marc4j. I can find all the 
> parts of the source code that seem to have a version number and change 
> them. I can make a git tag with the version number.
>
> But what else is entailed, how do people actually get marc4j?  I need 
> to update maven repo somehow or something? Anyone?