How can I use pem files in php's ssh2 functions

[nautilus2910]

I need to connect to some Amazon EC2 instances through php's ssh2 functions to get some info and display it on my backoffice.Is there a way in ssh2 functions to do the same I do when connecting through the command line ssh?\[code\]ssh -i path_to_file/key.pem host01-ec2\[/code\]Thanks