You guys may want to re-think your plans for this. From The Digital Bits:

We've done some digging with our sources at Universal, and we've learned the real reason behind their delay of the Dune: Extended Edition (previously announced for 5/10, but then pulled "indefinitely" with no explanation given). Those of you who are familiar with the film know that there's a longer version that's been shown on TV, credited to director Alan Smithee (a pseudonym used by directors when they want to distance themselves from a project for whatever reason). Well get this... after years of saying he would never revisit Dune, at the 11th hour director David Lynch decided that he wanted to be involved in the new DVD after all. Which means that when it's eventually released, not only is the DVD going to include the original theatrical version of the film... it will include a brand new "director's extended cut" edited by Lynch himself! No kidding.