So DFC does said co-pilot get to log PICUS when they fly the aircraft.
Here are the relevant parts of JAR-FCL;
Crediting of Flight Time;
The holder of a pilot licence,
when acting as co-pilot performing
under the supervision of the pilot-incommand
the functions and duties of a
pilot-in-command, shall be entitled to be
credited in full with this flight time
towards the total flight time required for
a higher grade of pilot licence, provided
that the method of supervision is agreed
with the Authority.
Logging of PIC Flight Time
A co-pilot acting as pilot-incommand
under the supervision of the
pilot-in-command on an aeroplane on
which more than one pilot is required
under the type certification of the
aeroplane or as required by JAR–OPS
provided such pilot-in-command time
under supervision (see (c)(5)) is
countersigned by the pilot-in-command.
PICUS (Pilot-in-command under
supervision)
Provided that the method of supervision
is acceptable to the Authority, a co-pilot may
log as PIC flight time flown as PICUS, when
all of the duties and functions of PIC on that
flight were carried out, such that the
intervention of the PIC in the interest of safety
was not required.
To answer the question in one simple sentence - No unless the operator has received approval for the method of supervision that is being applied.
I won't hold my breath for any SEP operator operating as 2 crew eg Simulated Instrument Flight getting approval for their "supervision system" if for no other reason that in all the cases where SEP's can be required to operate 2 crew there is no real option of providing the required supervision.