All you need for this is to buy a solid coloured panel from Stardesign. I normally use only white or black. You only need one and you need to put it somewhere in your suite in order to use it in your sceneries.
First, think of the pose you want. We're just going to do an extended arm right now. Then, cover the background with your panels.
Next, you want to arrange another one of your dolls so that their body part is sticking out where you want it. This part will look funny at first.
Now you're going to start covering the unwanted body parts with more panels. Leave the parts of the original me doll till the end as it makes things less confusing. I used two panels on both sides and one behind my doll in the middle.
After that you'll want to dress your me doll. Make sure that it doesn't look funny with the arms since they are no longer at the side of her body.
Finally, you'll cover up the me doll's original arms. This is the tricky part. Try to make the lines smooth. You'll have to make your panels very small so they fit nicely.
Here are some sceneries I've done with different poses. :]