If using worsted, work with two strands held together.
If using bulky, work with one strand.

There is a knitted version by Helen Flagg, here.

As of March, 2012, the requested size has changed, and the PDF has changed but the patterns in the forum have not. Please make the body 29-30” long. The total length (including the collar ribbing) should be 34”-35”. The requested width is now 15” across (flat measure), for a 30” circumference.

Also, the preference now is for bottoms that go straight across (not curved), to allow for more kick room.

Pattern is in forums here or available as a PDF below.