Wouldn't this do what you are asking for ....
https://vborg.vbsupport.ru/showthread.php?t=287620
No, this isn't exactly what I want. This just replaces the display of the postbit with replacement text, when I actually want that text to be part of the database, as in, that text should be editable as well. But it's close!
Edit: I looked around and found a mod that has a skeleton of what I want, but I don't know how to make use of it. This is from vBulletin 3 so I can't use it (I use 4.2.2), nor do I really want to, as this is not what I'm looking for. But this mod allows you to select one of the "canned replies" you wrote which will instantly write it out. I think that's what it does. This seems to be the relevant portion of the XML that I opened up:
<plugins>
<plugin active="1" executionorder="5">
<title>Canned Replies</title>
<hookname>global_start</hookname>
<phpcode><![CDATA[if ($permissions['cannedreplies'] & $vbulletin->bf_ugp['cannedreplies']['canusecr']) {
if (THIS_SCRIPT == 'newreply' OR THIS_SCRIPT == 'newthread' OR THIS_SCRIPT == 'infraction' OR THIS_SCRIPT == 'private' OR THIS_SCRIPT == 'showthread') {
$userid = $vbulletin->userinfo['userid'];
$crtest .= "$vbphrase[cannedreplies]: <br />";
$crtest .= "<select onchange=\"insertAtCaret(this.options[this.selectedIndex].value)\">";
$crtest .= "<option value=\"\"></option>";
$crs = $db->query_read("SELECT id, title, reply FROM " . TABLE_PREFIX . "cannedreplies WHERE userid=$userid || reply LIKE '{share}%' || reply LIKE '{share}%' ORDER BY title ASC");
while($row = $db->fetch_array($crs)) {
$row[reply] = preg_replace("#(\r\n|\n|\r)#s", "\r\n <br>", addslashes($row[reply]));
$row[reply] = str_replace('\"', '"', $row[reply]);
$row[reply] = str_replace("\'", ''', $row[reply]);
$crtest .= "<option value=\"$row[reply]\">$row[title]</option>";
}
$crtest .= "</select>";
} }]]></phpcode>
</plugin>
<plugin active="1" executionorder="5">
<title>Canned Replies Javascript AutoInsert</title>
<hookname>parse_templates</hookname>
<phpcode><![CDATA[if ($permissions['cannedreplies'] & $vbulletin->bf_ugp['cannedreplies']['canusecr']) {
if (THIS_SCRIPT == 'newreply' OR THIS_SCRIPT == 'newthread' OR THIS_SCRIPT == 'infraction' OR THIS_SCRIPT == 'private' OR THIS_SCRIPT == 'showthread') {
if (THIS_SCRIPT == 'showthread') {
$editorid = "vB_Editor_QR";
} else {
$editorid = "vB_Editor_001";
}
eval('$crjs = "' . fetch_template('cr_js') . '";');
$vbulletin->templatecache['pm_newpm'] = str_replace('<form', '$crjs <form', $vbulletin->templatecache['pm_newpm']);
$vbulletin->templatecache['newthread'] = str_replace('</head>', '$crjs </head>', $vbulletin->templatecache['newthread']);
$vbulletin->templatecache['newreply'] = str_replace('</head>', '$crjs </head>', $vbulletin->templatecache['newreply']);
$vbulletin->templatecache['userinfraction'] = str_replace('</head>', '$crjs </head>', $vbulletin->templatecache['userinfraction']);
$vbulletin->templatecache['SHOWTHREAD'] = str_replace('</head>', '$crjs </head>', $vbulletin->templatecache['SHOWTHREAD']);
} }]]></phpcode>
</plugin>
<plugin active="1" executionorder="5">
<title>Parser</title>
<hookname>parse_templates</hookname>
<phpcode><![CDATA[if ($permissions['cannedreplies'] & $vbulletin->bf_ugp['cannedreplies']['canusecr']) {
if (THIS_SCRIPT == 'profile' OR THIS_SCRIPT == 'private' OR THIS_SCRIPT == 'usercp') {
$cannedreplieslink = "<tr><td class=\"alt2\" nowrap=\"nowrap\"><a class=\"smallfont\" href=\"cannedreplies.php?$session[sessionurl]\">Edit Your $vbphrase[cannedreplies]</a></td></tr>";
$vbulletin->templatecache['USERCP_SHELL'] = str_replace('$vbphrase[edit_ignore_list]</a></td></tr>','$vbphrase[edit_ignore_list]</a></td></tr>$cannedreplieslink',$vbulletin->templatecache['USERCP_SHELL']); }
}]]></phpcode>
</plugin>
<plugin active="1" executionorder="5">
<title>Parser 2</title>
<hookname>parse_templates</hookname>
<phpcode><![CDATA[if ($permissions['cannedreplies'] & $vbulletin->bf_ugp['cannedreplies']['canusecr']) {
if (THIS_SCRIPT == 'newreply' OR THIS_SCRIPT == 'newthread' OR THIS_SCRIPT == 'infraction' OR THIS_SCRIPT == 'private' OR THIS_SCRIPT == 'showthread') {
$crdd = "<div class=\"smallfont\"> $crtest </div><br />";
$vbulletin->templatecache['pm_newpm'] = str_replace('<!-- / subject field -->', '<!-- / subject field -->$crdd', $vbulletin->templatecache['pm_newpm']);
$vbulletin->templatecache['newthread'] = str_replace('<!-- / subject field -->', '<!-- / subject field -->$crdd', $vbulletin->templatecache['newthread']);
$vbulletin->templatecache['newreply'] = str_replace('<!-- / subject field -->', '<!-- / subject field -->$crdd', $vbulletin->templatecache['newreply']);
$vbulletin->templatecache['userinfraction'] = str_replace('<!-- / note field -->', '<!-- / note field --> $crdd', $vbulletin->templatecache['userinfraction']);
$vbulletin->templatecache['SHOWTHREAD'] = str_replace('$vbphrase[message]', '$crdd $vbphrase[message]', $vbulletin->templatecache['SHOWTHREAD']);
} }]]></phpcode>
</plugin>
</plugins>
Not sure if this will help but I think answer lies in here somewhere!