I am sure you have done this but here is how I set up custom paper size for dot printers in XP. Using the add printer feature in printers. Select the aproriate dot printer and install the driver. Once installed, L click the dot printer and get it hi-lighted. Under file; select server properties, then check, select new form and put in the sizes you want. That seems to work on most weird paper sizes except for Power Church Ver 9 . Page 26 seems to confirm it. But, since a person can set custom paper sizes ??? 
Although I haven't tried it, no need to, It looks like you can define a custom paper size for any printer this way. Sorry for the long post. Dean M.