I used
http://vrgis.sourceforge.net/imagem_quilt.html and completed my first cathedral window quilt. There is also a great tutorial called sunshine creations that while googling stumbled onto involves a lot of ironing but great step by step. I also found today one on here great step by step it was cathedral window all hand sewn they had step by step with great pictures. I am currently working on a new cathedral quilt using the first sight I listed. Hope these few help