Just from toying around seems you click the cat head and drag to the clothes to remove the clothing from the chest, and then it simply seems to be just rapidly clicking with the mouse to inflate the breasts.
1. Click and hold on the cat face and drag the mouse off it and let go. Her cloths should come out 2. Go back to the cat face or her breasts and start clicking it as fast as you can, this acts like a pump that increases the size of her bust 3. When you click enough times, her panties should come off.
You can also turn on an Accessibility Option in the windows control panel called "MouseKeys." This will turn your numberpad into a mouse until you turn it off. Then you can press 5 on the numberpad to click, or use 5 and your mouse to be clicking that much faster.