Dry docking a turtle means cutting off their access to water completely for most of the day.
Is she small enough to fit in the water cup? If so, she's likely to just sit in it, and it's not heated, so that wouldn't be good for her.
Your best bet would be to give her a few hours a day in her tank (hopefully has a water heater in it) when you're not home (if you're at work or something) and bump up the temp in the tank by a few degrees to keep her warm in the water and then while you're home, take her out of the tank and keep her nice and dry in a box with towels in it. Being in the water for that time allows her to drink and go to the bathroom if she needs to, and you can also offer her food then (if she's eating still - hope she is!).
If you think she'll flip over in the box, make sure it's big enough for her to right herself inside it. You can use a household light over one end of the box to keep it nice and warm - just make sure she has the option to go under the towels so she's not under the bright lights the whole time she's in dry docking. It can be very stressful for them.
If you're going to keep her out most of the day, make sure you let her have a drink now and then in the tank every few hours.
Edit: Just found more of your posts stating that your water heater is broken! Ack. I'd buy a new one asap! A cold turtle is not a happy turtle and can soon be an even sicker turtle
