How to customize logout.html to force apache reauthentication?

Hi folks,
I’ve set up RT to use web external authentication via Apache, however I
could’t find a way to force reauthentication after logging out so a
different user can log in.
It seems like the previous authenticated session is saved and that
causes my browser (firefox 1.5) not to ask for authentication anymore.
My guess is that Logout.html should be customized to do so, but not sure
about it. Any guess ?

Here is my apache conf:
<Location /rt>
Options None
SetHandler perl-script
PerlHandler RT::Mason

AuthPAM_Enabled on
AuthName "Request Tracker"
AuthType Basic
require valid-user

<LocationMatch “/rt/NoAuth”>
Satisfy Any
Allow from all

<Location /rt/NoAuth/images>
SetHandler default-handler

Here is my
Set($WebExternalAuth , “true”);
Set($WebFallbackToInternalAuth , “true”);
Set($WebExternalGecos , undef);
Set($WebExternalAuto ,“true”);

FYI I used PAM SMB to authenticate against Active Directory and that
piece is working fine.
Any help will be very appreciated !