Login using ThinkFinger

Modify the file /etc/pam.d/common-auth

#
# /etc/pam.d/common-auth - authentication settings common to all services
#
# This file is included from other service-specific PAM config files,
# and should contain a list of the authentication modules that define
# the central authentication scheme for use on the system
# (e.g., /etc/shadow, LDAP, Kerberos, etc.). The default is to use the
# traditional Unix authentication mechanisms.
#
# thartono-original (below)
#auth required pam_unix.so nullok_secure

auth sufficient pam_thinkfinger.so
auth required pam_unix.so try_first_pass nullok_secure

#Add your fingerprint in the known fingerprint database
sudo tf-tool --add-user thartono

Now you could login using your userid and swipe your finger !