I just looked at the shoutbox hack and it should be fairly easy to add it to your myvbindex instead of your forums index. You would just follow the instructions there, and when you get to the part about adding some code in your forums/index file before
PHP Code:
eval("dooutput(\"".gettemplate('forumhome')."\");");
You would add it before this part at the end of your myvbindex file instead:
PHP Code:
$getbgrow=getrowcolor();
eval("dooutput(\"".gettemplate('index')."\");");
Then you would add the $the_shoutbox variable in your index template wherever you would like it to appear instead of your forumhome template.
I've never tried adding that feature and never even downloaded that hack until today, but those should be the only changes you would need to make. If for some reason that doesn't work let me know and I'll test it out.