[imp] horde templates / imp login screen

[Liam Hoekenga]

Is it possible to embed PHP in the new horde template system?

Here's my problem... we're using a our own auth handler, which 
automatically sets the Horde user name to the value of $_SERVER[ 
'REMOTE_USER'].  We run a local instance of up-imapproxy, and Cyrus 
proxyd configured such that proxyd doesn't require user passwords.

This works great most times, but occasionally, the the user may get 
presented an IMP login screen, and if they type in a user name other 
than their own, they get that access to that user's email (bad).

So, in horde 3.0.x / IMP 4.0.x, we'd added this  check to 
imp/templates/login/login.inc

<?php if( $conf['auth']['driver'] == 'cosign' ): ?>
<input type="hidden" name="imapuser" value="<?php 
echo($_SERVER['REMOTE_USER'])?>" />
<input type="hidden" name="password" value="<?php 
echo($_SERVER['REMOTE_USER'])?>" />
<?php else: ?>

such that if the login screen ever was displayed, users could only click 
ok.  I was trying to impliment something similar in the the IMP 4.2 
imp/templates/login/login.html, but it doesn't seem to be working.. 
which makes me think that the horde template engine doesn't allow 
embedded php?

Any suggestions for how to accomplish this?

Liam