Originally Posted by My Manual :P

1) Run SQL Query:
INSERT INTO datastore (title, data) VALUES ('maxguests', '')





2) Open online.php in forum root

Find:
$recordtime = vbdate($vbulletin->options['timeformat'], $vbulletin->maxloggedin['maxonlinedate']);

add below:
if (intval($vbulletin->maxguests['maxonline']) <= $numberguests)
{
$vbulletin->maxguests['maxonline'] = $numberguests;
$vbulletin->maxguests['maxonlinedate'] = TIMENOW;
build_datastore('maxguests', serialize($vbulletin->maxguests));
}
$guestrecordusers = $vbulletin->maxguests['maxonline'];
$guestrecorddate = vbdate($vbulletin->options['dateformat'], $vbulletin->maxguests['maxonlinedate'], true);
$guestrecordtime = vbdate($vbulletin->options['timeformat'], $vbulletin->maxguests['maxonlinedate']);






3) In Languages & Phrases/ Phrase Manager/ Add New Phrase:
Phrase type: GLOBAL
PRODUCT: vBulletin
Varname: most_guests_ever_online_was_x_y_at_z
Text: Most users ever online was {1}, {2} at {3}.





4) In template 'Forum Home Templates/FORUMHOME'

find:
<div style="white-space: nowrap"><phrase 1="$recordusers" 2="$recorddate" 3="$recordtime">$vbphrase[most_users_ever_online_was_x_y_at_z]</phrase></div>


and replace with:
<div style="white-space: nowrap"><phrase 1="$recordusers" 2="$recorddate" 3="$recordtime">$vbphrase[most_users_ever_online_was_x_y_at_z]</phrase>
<br />
<phrase 1="$guestrecordusers" 2="$guestrecorddate" 3="$guestrecordtime">$vbphrase[most_guests_ever_online_was_x_y_at_z]</phrase>
</div>