Add to archive "FileName.xpi"

I use WinRar.

In Options > Settings > Integration > User defined archive extensions, I've associated XPI and JA files with the program.


I would like to add the following entries to Windows Explorer's context menu:

1) Add to archive "FileName.xpi"
2) Add to archive "FileName.ja"


I'd like the entries to appear below the default "Add to archive 'FileName.zip'", and also the compression format to be in my zip settings.


(Win 7, 32 bit).

Thank you.