PubMed Central ID numbers

The National Institutes of Health has a new policy to include PubMed
Central ID numbers on citations resulting from NIH-sponsored grants when
writing grant applications, progress reports, etc. What is the best way
to use EndNote to support this?

My thinking is to modify the Journal Article reference type to include a
custom field called "PMCID". The PMCID data will be manually entered
since PubMed and other databases don't yet include that information in
downloaded citations. The actual entry will be "PMCID: 123456" or "NIHMS
ID: 123456". Then create a new output style which includes the PMCID
custom field in the appropriate spot in the bibliography citation.

What are the implications with the traveling library if another user
hasn't modified their reference type? Is there another way to approach
this?

Thanks!

Jayson Felty
Southwest Foundation for Biomedical Research