Its really simple. Go to the following link and read about IRLP.
http://www.irlp.net/ or purchase the book
VoIP: Internet Linking for Radio Amateurs from the ARRL or another book seller. You need to find the local repeater or simplex node. This can be from the Repeater directory or local coordinator. It is a matter of just sending the access tones to establish the link, just as you would if using the autopatch. Regards, Don