Cisco Firewall :: Setup SSL VPN With Two-factor Authentication On ASA5510 With Software Version 8.0(4)?

I am trying to set up SSL VPN with two-factor authentication on an ASA5510 with software version 8.0(4). I want to use LDAP for actual authentication and user mapping, but require a valid certificate signed by a particular local CA to connect.I have imported the CA's root certificate, signed an identity cert for the ASA box and imported, and assigned the cert ("trustpoint")  to the outside interface.Under the connection profile itself (for DefaultWEBVPNGroup), there is an option to select authentication method as AAA, certificate or both. AAA works as expected, authenticating against LDAP. If I select certificate or both, I get rejected with Certificate Validation Failure regardless of if I have a valid signed cert or not. This is what I see with "debug webvpn 100":
 
webvpn_portal.c:ewaFormServe_webvpn_login[1904]webvpn_portal.c:http_webvpn_kill_cookie[682]webvpn_portal.c:ewaFormSubmit_webvpn_login[1964]ewaFormSubmit_webvpn_login: tgCookie = 0ewaFormSubmit_webvpn_login: cookie = c98f3940ewaFormSubmit_webvpn_login: tgCookieSet = 0ewaFormSubmit_webvpn_login: tgroup = NULLTunnel Group: DefaultWEBVPNGroup, Client Cert Auth Failed!Embedded CA Server not enabled. Logging out the user.webvpn_portal.c:ewaFormServe_webvpn_login[1904]webvpn_portal.c:http_webvpn_kill_cookie[682]
 
So, it seems the ASA is only trying to check the cert against a (nonexistent) ASA-based CA. How do I get it to check against an external CA cert?Under "Remote Access VPN -> Network (client) Access -> AnyConnect Connection Profiles", I have ticked "Allow Access" and "Enable DTLS". There is also an option "Require client certificate" which doesn't seem to do anything - whether or not I check it, I can connect and authenticate to the VPN with or without signed certs as long as the previous setting is "AAA".

Some highlights from the config:

crypto ca trustpoint ASDM_pfirewall01.company.tld enrollment terminal fqdn pfirewall01.company.tld subject-name CN=pfirewall01.company.is,O=Company,C=IS,L=Reykjavik keypair company crl configurecrypto ca trustpoint ASDM_TrustPoint0 revocation-check crl none enrollment terminal crl configure  no enforcenextupdate  no protocol ldap  no protocol scepcrypto ca trustpoint ASDM_pfirwall01.company.tld revocation-check crl enrollment terminal no client-types crl configurecrypto ca certificate chain ASDM_pfirewall01.company.tld certificate 02    30820598 30820480 a0030201 02020102 300d0609 2a864886 f70d0101 05050030     <snipped rest of cert>  quitcrypto ca certificate chain ASDM_TrustPoint0 certificate ca 00e2a6f08003ded6c9    3082054e 30820436 a0030201 02020900 e2a6f080 03ded6c9 300d0609 2a864886     <snipped rest of cert>  quitcrypto ca certificate chain

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