Hello Werner,
simply put:
the new POP should have two PE nodes and at least two core facing links to the existing backbone
Depending on the network design the new POP may be multihomed to two different POPs or it has two links to the same existing POP.
The core facing links will be part of OSPF, LDP, RSVP TE and iBGP using loopback addresses complete the solution.
MTU has to be great enough to support current services and services you would like to enable in the near future.
if the network area 0 is not too big you can add the new POP in area 0.0.0.0 this is specially useful for MPLS TE.
Hope to help
Giuseppe
