Retrieve list of specific users subscriptions

I am in the process of coding a YouTube sub for sub website(with functionality similar to that of subxcess), however I have found myself needing help with a specific part... how can I retrieve a specific users list of subscriptions and order these subscriptions by name?

The reason why I am asking is that I want to check an authenticated users YouTube channel subscriptions against YouTube channels already in my database who are requesting to be subbed ie. I don't want to display channels that the user is already subscribed to. I just want him / her to have the opportunity to subscribe to user they are not already subscribed to.

I would really appreciate some help with this guys, and who knows, very soon there might be another YouTube sub for sub website that we can all use.

Btw I forgot to mention I am coding in PHP.

Bump!

it's all on youtubes data api page;

code.google(DOT)com/apis/youtube/2.0/developers_guide_php.htm
&
code.google(DOT)com/apis/youtube/2.0/developers_guide_php.html#Retrieving_a_Subscription