I'm not sure! Try it and I'll let you know if it works.
If you have to submit a full entry you can hide it from displaying on your creator page in the theme editor.
Otherwise you can post it here in the forum, though it won't be rateable for the jam.
Viewing post in does the project uploaded to the jam has to be public?
You can post it on the submission thread if you'd rather not make a public submission.