Kostiner easel pen line blades...How do you use them?

I picked up some used equipment from a pro lab getting rid of its darkroom gear. This included a 20x20 kositner easel which, alas, came without any blades. I purchased a set of 8 blades for this easel from an eBay trader which included; a standard four blade set , a 1 1/4 inch wide set of two and a 3 inch wide set of two 'pen line' blades. The four standard blades are used like any other four blade easel but it's not apparent to me how I'd use the pen line blades. If at all possible, Ill print a thin margin of the film rebate to 'frame' the image but this isnt an option when cropping. I love the look of the rebate 'pen line' and would really like to be able to create this effect with my new easel. Any insights?
Regards
Adam

You are going to think this sounds crazy, but, what you do is put a set of 2 of the 3 inch wide blades fixed to the easil after you have exposed the print, with the set of blades with an accordion cover in between that protects the print while exposing black borders (two sides at a time). see here and imagine.
http://35mm-compact.com/forum/viewtopic.php?f=13&t=48400

Thanks, guys! The pdf manual is particularly helpful.
Regards
Adam