Depends. I've never seen the Foundation as actually having very advanced defenses against metaphysical beings—as far as I've ever seen them, they're too paranoid of such things. That being said, just because you can easily get into there doesn't mean you'll get out. Your best bet would be to use some sort of scrying and some sort of teleportation that the SCP Foundation doesn't have a defense against.
L. S. isn't my character, but I doubt he'd be really easy to contact.
However. It should be noted that SCP-239 is locked up for an extremely good reason. Her fears, her biases, all become real. If she is afraid of a monster under the bed, it will exist, and it will quite possibly kill someone. If she believes that someone is evil, they will be mind-raped into that position. If she thinks that you're mean, you're mean. If she thinks you're nice, you're nice. Convince her that <insert politician here> is an evil nasty man or woman, and you turn them into a Hitler parody.
The problem is that she isn't just a reality bender, she's a reality bender who doesn't have to will things to make them happen. Even an ordinary reality bender is dangerous enough. She is so incredibly dangerous that other members of the Hand would very likely try to either remove her abilities or render her unable in some manner to be a threat. That would not necessarily be a pleasant process for her.