From LASORS:
"The JAR-FCL Committee has agreed that the Proficiency
Check required to re-validate the stand alone PA 46 type
rating flown in a piston-engine variant, could also serve
to re-validate a Single-Engine Piston (SEP) Class Rating.
Also, as single-engine aeroplane Instrument Ratings (IR)
are not class or type specific, an IR re-validated on any
single engine aeroplane will be valid for use in a PA 46. By
combining the IR re-validation with the PA 46 re-validation
every year, a pilot could keep a SE IR, a PA 46 type rating
and a SEP (Land) class rating valid, all on the basis of
one combined flight test, providing that the examiner
conducting the test was authorised for the purpose of both
the PA 46 type rating and IR proficiency checks."
Never heard of the SEP having connections to a CJ though.