The idea of the Pi Shawl is that you can adapt any lace pattern to fit the shawl, so if you aren't doing the basic version that Elizabeth describes in the Knitter's Almanac, then the possibilities are endless.
How far into your shawl are you? Too far to think of frogging and starting again with larger needles? In the Knitter's Almanac, EZ talks about using needles size 7 to 10.5 on her shawl.
You might want to see if you can get a copy of the Knitter's Almanac and see what EZ herself has to say about the Pi Shawl. That may help you get through it with more enthusiasm.
Hope this helps!