OpenVPN with Google Authenticator ?

Hello,

is it possible to run the dd-wrt integrated OpenVPN server together with Google Authenticator or any other 2-factor-authentication tool providing One-Time-Passwords? Has anyone tried something like this?

I found decent tutorials on how to setup OpenVPN with Google Authenticator for Ubuntu! Would these also work out with dd-wrt using the same commands and steps?

www.howtoforge.com/securing-openvpn-with-a-one-time-password-otp-on-ubuntu
https://vorkbaard.nl/setup-openvpn-with-google-authenticator-on-ubuntu-12-04-lts-server/
http://askubuntu.com/questions/301380/how-to-use-google-authenticator-with-openvpn-server-on-ubuntu-12-04