I've only seen published procedures for SLOP in Oceanic flight.
China permits up to 3 miles RIGHT with no ATC clearance required (See Jep manual). But, with their recent implementation (last year) of RVSM, the ATC in China is regularly issuing off-set instructions when more than 2 aircraft within 100 miles of each other (different levels). Most believe there's a bit of a ATC fear factor involved.