I was curious about this too.  I contacted the California Air Resources
board.  They sent me a copy of the Executive Order proclaiming the
"legality" of the TiiCo conversion (D-573).

If you're curious, have a look at it.  I've posted it to the TiiCo yahoo
group in the "files" section.  Seems pretty legally binding to me.

http://autos.groups.yahoo.com/group/tiico/

A few weeks back I tested it -- I had to smog my TiiCo'd van.  The only
problem I had was that my local smog dood wasn't really used to looking at
an EO.  He was puzzled to say the least.  He made a few phone calls, then
gave it the once over.  Pass!

Ryan in Half Moon Bay, CA.