Pam module to dynamically use different two factor services based on what the user prefers
Coming soon(tm)
in /etc/pam.d/test:
auth required pam_unix.so nullok_secure
auth [success=1 default=ignore] /path/to/pam_twofactor.so use_first_pass
auth requisite pam_deny.so
auth required pam_permit.so
Remove use_first_pass to test that the module asks for two factor correctly..