You should not have any problems doing original cataloging, either
full or minimal level, directly on NOTIS.  That is how all of the
original serials cataloging is done at Notre Dame. After cataloging,
I make printouts which are then routed to the serials copy cataloging
staff for input into OCLC. This staff knows how to "translate" the
fixed fields from NOTIS to OCLC MARC. And, for those titles which
you do not circulate, or consider loaning on ILL, or whatever reason
want to keep "secret" from the rest of OCLC's members, you could
do these "in-house" only.  This is what we are doing for telephone
directories kept for reference use only.
Jean Pec
Serials Specialist
Univ. of Notre Dame
Notre Dame, IN 46556
219-239-6904