how to handle an aggressive stray

get some interactive toys that you can play with her with...see how she reacts to that

One of the things you will come to learn in rescue is that you can't save them all, and for some, they really are happier if you TNR them - they are just too far gone to be housepets (whether they were once owned or not, sometimes its just too late)

Without seeing her, its hard to tell, but do not do anything that would make her scared of you (think how many tame housepets are terrified of brooms)

Please PM hissy about this, she will have advice. I believe wearing padding, long leather gloves and using cardboard as a shield is the way to go to get in to manage litter, food and water. Why is the kitty in your home? I'm pretty sure she doesn't recommend socializing ferals older than three years. If kitty is there because he/she needs medical attention.... ????? Definitely ask MA how to handle it.

That actually sounds more like a feral to me, they often bond with the person who socialised them and are still fearful of other people despite how much time they spend with them

Which doesn't contradict the information Eithne wrote. She bonded to that person.

Please PM hissy if you haven't.

If she is aggressive, why in the world do you want to pet her? Strays with feral tendencies (which is what this cat sounds like to me) are wary of any strangers in their world. They are fearful fo humans (especially if they have bad memories of what people have done to them) The rescuer who initially took this cat, knew what she was doing and worked over time to gain a bond. You can't replicate that overnight and you need to stop expecting this cat to respond like a house cat would. It won't happen. Sounds like her defenses are up and she is on guard every time you enter the room.

Ignore her for now
Set up a feeding time schedule and care schedule and stick wth it. They love routine. Don't pull any surprise visits, just set your times and stay on them.
Don't make direct eye contact at all- if you do, blink your eyes slowly three times, lower you head and back away.
DON'T take a broom in the room- brooms are what people who hate cats use to chase cats off their patios, porches and garages.
Lower the lighting in the room- I burn night lights. The cat can see me, and not get hit with a bunch of glaring lights everytime I open the door.
Create caves in the room where the kitty can hide and feel safe. Make it vertical space not horizontal.
Play harp music non-stop- there are some really good CD's out there now that they use for therapy in aggressive cats. LDG has a link to one CD- I lost my bookmarks recently.
If you are stressed, don't go in the room. She will respond to your stress level and become on guard.
She also sounds like she might be ill- have you taken her to the vet? Lip smacking is not a aggressive behavior, it is usually because the kitty has an upset tummy. If you aren't finding vomit in the room, she could be eating it as they do this to get rid of the scent (it draws in predators)
Just quit expecting her to DO and just let her BE who she is. You will find your way to her in time, but it is her timeline- not yours.

If you like, I have a friend in Northern CA who rescues. I can call her and see if she has room for your cat with her colony.