TROY, Mich. - The 49ers arrive at their hotel yesterday in minus-8 degrees and are surprised by head coach Bill Walsh dressed as a bellhop taking their luggage. The Bengals arrive 24 hours later tonight in 10 degrees and head coach Forrest Gregg is wearing a no-nonsense tie six days from Super Bowl XVI when he denies a busload of media access to his players even though they have journeyed the 24 miles from NFL media headquarters in Dearborn, Mich. It may be the first northern Super Bowl ever, but since Gregg played in the very first one anywhere 15 years ago he’s not very impressed.