Broken pg_class table

[Roger Ging <roger@xxxxxxxxxxxxxxxx>]

I accidentally wrecked the pg_class table in a database by leaving off 
the where clause of an update statement when setting the reltriggers 
back to the count from pg_trigger after a bulk data load.  I can no 
longer connect to the database, although it does start up without 
error.  running psql [dbname] causes extreme cpu load, and the command 
just hangs.  Memory usage continues climbing until a oom killer crashes 
everything.  I presume that my blunder is causing some sort of infinite 
loop during postmaster startup for the spawned process.  Is there a way 
I can get direct access to the file for pg_class and reset the 
reltriggers to the correct values without a full dbinit process?