Question about "subject to" investing

[Jeffrey De Los Santos]

So, I have been learning about subject to deals and other seller financing strategies that I believe will help me in my real estate investing career, but I have questions about this strategy.
I asked my title agent if she knew how to close a subject to deal and she said she does. She also mentioned that in order to pull off a deal like this, the title company would need a written approval and instructions from the lien holder. Im in the state of Pennsylvania and was wondering if this is what needs to be done in order to successfully acquire a subject to deal? 
Your response is greatly appreciated!