Based on your brief description of what you intend to do, yes --- can't.
I'm not sure how I could be any more specific without actually telling you what the app does. Basically can you make custom buttons in the lock screen appear in a similar fashion to the way the previous (<<), play (>), and next (>>) buttons appear when the home button is double tapped.
Also, not being in a paid program is going to significantly limit asking questions like this and understanding responses here, so...
Why is that? Its my understanding that paying the $99 means the app can actually go on the store and you can test it on a real device vs the emulator. The whole reason I was asking this question was to determine if an idea me and a buddy had was capable of being done before investing money in it.