Yes, you can.
The API is undocumented, however descriptive identifiers are used for function names, table names and variables. The code has been broken down into modules and functions, which means integration would be possible.
The passwords are stored using the standard MD5 hash. Standard PHP sessions are used for the login, and the login code is in a function.
Please note that the script source code is under copyright, and remains under copyright when integrated with 3rd party software. Our license does not grant the rights to sale or distribution of the copyrighted software, either in its entirety or modified form.