I am installing a shower in my basement and have to raise the floor 6" so i can use a "Sanigrind" macerater.How do I build the base of the shower?

You don't need a macerator for just a shower, is this a full bathroom? You could run the shower drain to an ejector pit. Please tell us more about what you are doing.

I am installing a complete bathroom.The Water Closet will go into the macerater along with the waste water from shower and sink. I just need to know how to build the base for the shower.

I think you may be looking at the wrong Saniflow. Did you know about this one, it goes inside the wall and would not require the shower to be 6" higher. Saniflo's Sanipack Up Flushing Pump (http://www.plumbingmall.com/saniflo_sanipack.htm) You may stile need a raised shower to get some pitch to your drain. I would probably just pour a concrete pad