For Usernames:
Insert this code into the header, modifying the User, to the user you wish to change the color of.

<script type="text/javascript">
/*<![CDATA[*/
function user(username) {
if("User" == username){
document.write('<span style="color: #800000;">Landae</span>');
} else {
document.write(username);
}
}
/*]]>*/
</script>

Replace [username] variable with this:

<script type="text/javascript">/*<![CDATA[*/ user('[username]'); /*]]>*/</script>

For Userlevels:
Insert this code into the header, modifying the Userlevels, to the userlevels you wish to change the color of.

<script type="text/javascript">
/*<![CDATA[*/
function level(userlevel) {
if("God Admin" == userlevel){
document.write('<span style="color: #800000;">God Admin</span>');
}
else if("Moderator" == userlevel){
document.write('<span style="color: #008000;">Moderator</span>');
} else {
document.write(userlevel);
}
}
/*]]>*/
</script>

Replace [userlevel] variable with this:

<script type="text/javascript">/*<![CDATA[*/ level('[userlevel]'); /*]]>*/</script>