EAP - TLS Client Certification Stored Removable Media

Hello All; I have a question about EAP - TLS . How can I configure client certification stored from removable media (ex: usb memor, smartcard, etc..). I have already used EAP - TLS with client certification stored on Windows (cliet) but i need a solution that user can authenticate when insert his usb memory and logout when remove his usb memory ? My system running with EAP - TLS authentication and LDAP authorization and clients are use 802.1x ... Thank You For Your Relation, Aydin Kocak, TURKOM.