Sign up using gmail account into my application

Hi,

Want to know is there any blog or tutorial to guide for how to sign up
using gmail account in rails.I am using rails version 2.3.5 and i
can’t use omni-oauth gem and i am using restful-authentication for
authentication.currently i
done sign up using facebook account with the help of facebooker plugin
with restful-authentication.Please help
me out with this one.

Thanks & Regards,
Prashant