Click on Tools --> Preferences.  Then choose Files --> Settings.  Choose Add and put "Miva" in the description
blank, and add "mv" in the extension blank. (no quotes).  This will make edit plus recognize .mv extensions.

Then go down to Syntax, choose add.  Browse to the miva.stx file you downloaded and select it.  The extension
should be "mv" here as well. (no quotes)

Then go down to filters.  Add "Miva" for the description, and add *.mv for the wildcard.

Make sure the files you downloaded are in your c:\program files\edit plus directory.  It will automatically
recognize the miva.ctl file and it will be available if you turn on the cliptext window with the "View" menu.

After you make these changes, exit out of edit plus and restart it, open a .mv document and there you go...