Edit Comment Author and Date

Hey,
This may belong in the themes section, but it is not related to any particular theme, it is not within the theme code.

What I am wanting to do it display the comment author and time on the same line.
Currently is displays like this:

Author says:
Posted on Month Date, Year at Time

I want it to display like this:

Posted by Author on Month Date, Year at Time

I cannot seem to change this is any of the theme files, but it can be changed in the wp-includes/comment-template.php
I have tried a few things but I cannot get it al to display on one line.
Does anybody have any suggestions? It may be able to be done through css but I’m not sure.
Any help is appreciated.
Thanks