Painting Paneling can be a difficult project in the fact that you WILL need to prime it and that can be messy. The stain that usually is on the edges of each panel will bleed through paint and alot of primers. In the 10 years of painting I have painted dozens of paneled rooms.
What you need to use is B.I.N. primer http://www.zinsser.com/product_detail.asp?ProductID=10
. This can be tinted towards the color you will be using too. You will need to protect your floor with a poly carpet cover and drop cloths. Also, you will need to use a brush to get it in the crevices where the molding is and cut in, use a 1/2 nap roller for the remaining parts.
Once primed and dry you may caulk or use spackle then paint it as you normally would. Following this procedure will provide a professional finish that will last and not bleed. The paneling before starting should also get a slight sanding with 120 grit to scratch the surface for better bonding with the primer. Use a pole and a sandpaper holder.