The 2010 SCCA Time Trials Rules are available direcly from the SCCA web site.
http://cms.scca.com/documents/Club%20Forms/2010%20Tech%20Forms/2010%20Time%20Trials.pdf
These cover all levels of SCCA Time Trials events, from Level 1 "PDX" up thru Level 4 "Hillclimbs" including car elegibility, safety requirements, and participant requirements.