If This Is It - Personal Version

I am very new to creating custom DLC.  I have created one for personal use for practice purposes but nothing on the scale of a song... yet.  Unless someone specifically wants it, this will be strictly for personal use and will not be published.

I found a version of If This is It by Huey Lewis and the News but it only has the bass line.  I found a guitar pro tab also that seems pretty accurate.  So I took the psarc file and brought it into the editor and was able to get the EOF file.  I then was able to figure out charting the song for lead guitar, rhythm guitar and bass.  It's not perfect but is a decent EOF file.  I added a few additional seconds at the beginning of the song as well and re-encoded the file.  I'm wondering what my next steps are to get everything back into the psarc file.

Do I need to redo the audio portion since I added some time at the beginning?  There was a vocal file included also.  Will I need to redo or adjust that?  How do I get the different tracks from EOF into a format the the editor will accept?  I only see the 1 file and the rhythm guitar is loaded.

Sorry for the bunch of questions.  I just need a little guidance as to what steps to perform.  Thanks in advance.