Well, if you search in showthread.php for:
PHP Code:
if ($vbulletin->userinfo['userid']) // fakes the user being in this thread
I think this is start of the part that adds the current user. A little below that is:
PHP Code:
eval('$activeusers = "' . fetch_template('forumdisplay_loggedinuser') . '";');
So that starts creating the value of $activeusers by adding the current user (which I guess is why you always show up first on the list).
Then below that is a loop which starts:
PHP Code:
while ($loggedin = $db->fetch_array($threadusers))
That looks like the part that adds all the other active users, one at a time. A little below that is:
PHP Code:
eval('$activeusers .= "' . fetch_template('forumdisplay_loggedinuser') . '";');
The ".=" appends to the string, so that line adds one more user.
Since you are using misc.php whihc doesn't have this code, $activeusers (which appears in the part of the template you borrowed from SHOWTHREAD) will be blank.
So, you could try copying the block of code between these comments:
PHP Code:
// *********************************************************************************
// Get users browsing this thread
.
.
.
// *********************************************************************************
// get similar threads
But I don't know, it might not turn out to be that easy. The thing I'm wondering about is that the comment says "Get users browsing this thread". I haven't studied the code, but if that comment is accurate, it could mean that it won't do exactly what you want.
ETA: ...also, there may be important things that happen in the code before the block I mentioned above, in which case you may need to copy more that just that block.