At that young age, some accidents can be expected. With that said, I haven't had a problem, though.
A few suggestions...
If you catch her peeing/pooing elsewhere...you can carefully/quietly/lovingly place her in the cat box. Don't do anything to scare here while she is peeing/pooing, though...even if it's in the totally wrong place. If she is scared, she will be encouraged to find a more private hiding place to do her business. She doesn't know the difference at this point.
Put her in the litter right after she eats. Establish the routine for eating and pooing, to help her figure it out. Typically, they will need to potty right after they eat, especially at that age.
Confine her to a smaller area, one room - bathrooms are good. Food, water, and litter...keep a good distance between litter and food. They don't like to potty right by where they eat. It's instinct. Confinement seems mean, but just a couple of days to establish what the box is for should help. Kittens that small aren't ready to have full run of the house anyway, in most cases. Go in and check on her frequently, if she's just used the box, then let her out for awhile. At that age, I normally only let them loose when their "tank" is empty.