OK I have some suggestions, but first, this is CRAZY. I dont let my 4-year-old act that way.
OK now I think all children need choices, all children have a reason for doing certain behaviors, and eventually there is a solution.
First you have to find why she is doing this. You hinted that you believe she may want to be babied, you taking care of her, and without saying so it seems she is searching for power. Many children will protest so they have power, especially since they usally have little control in their day.
Second which goes with the first, she may need choices. Since you already have conversations with her you should try to find why. Ask her if she likes you taking care of her or maybe she likes making you do it (im sure she wont say that). Maybe finding other alternatives that are appropriate that show you taking care of her, and tell her to choose those. Make sure they are really great choices so she will want to choose those over you dressing her. Here are some choice ideas: special long cuddle time at night with a story, helping her do her hair really pretty, painting her toes (my dd loves that), special movie night, game night, playing dolls.
Another approach all together: This week I have started a chore chart for my 4yo. I am going to pay her .25 for each chore she does each week. I used a website called handipoints to create it. I put in normal and special chores. They also have games for kids to play online. You could sit down and create it with her and tell her that is one of her chores "to get self dressed". If she is resistant at first you could make that one worth more. After 2 days of doing the chore chart I am going to add an extra line myself for behavior, so if my dd makes several bad choices in day it will show. I sat down and made the chart with her and talked about rewards. She decided she wants to buy the new thumbalina movie. So tomorrow I am going to print a picture of the movie, the price, and how many quarters it will take to get there. (just to show her value, money, math)
Proud mommy to Corbin:7, autism/epilepsy; Kayla:5, my bff; and Collin: 9/10/09. M.Ed. Early Childhood. Wife to my OT hubby. Breastfeeding, babywearin, home cookin SAHM.