Jayne, My "technique" for pit firing? Simple: drive to Colorado and sign up for a pit firing session with Sumi von Dassow at Washington Heights Arts Center in Lakewood, CO. I am embarrassed to say that as I was mainly interested in techniques that I could bring to trash can/sawdust firing, I didn't pay very much attention to the actual pit construction. I've tried to find photos from the trip for you but it appears that my computer has eaten them. I SEEM to remember that the pipes had slashes cut in them rather than holes, but I could be mistaken. And the blower looked very much like a large leaf blower, but it would have to have been one with an on/off switch, not a trigger-type start. What I did learn and remember that has helped my firings is to stop using porcelain (I switched to Laguna cone 5 B-mix), lower my bisque temp to cone 010, and add copper carbonate rather than just copper sulfate (found in MiracleGro). She recommends the use of terra sigillata, but I prefer just to burnish my pieces.
As to why Bonnie Staffel would use Pet Litter, I am just guessing that she is referring not to cat litter but to the wood shavings used as bedding for many pets. It's larger than sawdust, won't pack as densely, and will therefore fire hotter and quicker, vaporizing your chemicals better without just smoldering and producing mainly shades of black and gray like fine sawdust. I go to a feed and grain store here in Kansas City and buy aspen wood shavings. It may be my imagination but I think I get better colors with the aspen rather than cedar shavings.
My apologies if I've gone on too long, but as someone who has lurked on this forum for well over a year, it's nice to be able to share, if only a little bit.