It is actually quite easy to do. In LDraw Pattern Creator you simply press 'File -> Import from DAT' and then choose the direction of projection. You then get three import options. If you want to the template to appear as the supplied templates then you should pick the bottom option: 'Overwrite and import projection data'. Then you can pick a part from the LDraw parts library and use that as a template.
I would however recommend to open the part in and a part editor tool, like LDPartEditor, first to isolate the surfaces you want the pattern to be moddeled on. Of course you would have to save it as a seperate '.dat'-file so you will not ruin the original part.
I would however recommend to open the part in and a part editor tool, like LDPartEditor, first to isolate the surfaces you want the pattern to be moddeled on. Of course you would have to save it as a seperate '.dat'-file so you will not ruin the original part.