X509 Client certificate - how to prompt user for Master Password

Hi There,
I'm working with the SWT Browser widget inside a Web Browser view I am
creating and I am trying to get it to connect to a SSL enabled website
that requests a clientside certificate. I'm using XulRunner 1.8
(Mozilla 2) in Java i.e JavaXPCOM.

I can use nsIX509CertDB to import the PKCS12 keystore that holds the
client side certificate and so long as the browser then remains open I
can connect to websites requesting my user cert without problem.

However, when I restart the browser I can no longer access the SSL
enabled site, the client certificate is still in there (I can see that
by calling findCertNicknames). It doesn't prompt me for a password for
the keystore which I am guessing is the problem (i.e. the session
where I import it the password I use on the keystore remains in memory
to be accessed, when I shut it down and restart it the password isn't
known, its not asking me for it and everything is failing quietly.)
The only way I can then get it to work is to blow away the user
profile and reimport the cert with password etc, not exactly a
suitable solution.

Does anyone know how to get XPCOM to prompt the user for the password
to mozillas user cert keystore? Or method by which I can provide the
password to XPCOM programmatically?

Thanks!
Will.