I had that same Popular Mechanics book
Melt enough paraffin to cover about 1/4 inch of an old pie pan,,,
Pull the bullets out of .22 rounds and dump the powder,,,
Push the brass into the paraffin and pull it back out.
You now have a paraffin wadcutter suitable for shooting in your garage.
The Quick-Draw people have been doing this for quite a while now,,,
Not the pie plate thing but molded wax bullets for revolvers,,,
S.A.S.S. shooters are starting it for indoor winter fun.
I read an article recently that supports what Pahoo said,,,
They modify the brass to take shotgun primers.
Here's a wikipedia article you might find useful,,,
http://en.wikipedia.org/wiki/Wax_bullet
Also google this:
"quick draw" + "wax bullets"
It's feasible to do and has the potential for a lot of fun,,,
I just shoot pellet and air-soft pistols in the winter,,,
I'm a bachelor so only my cat cares.
Hope this helps,,,
Aarond