Pedigree Forge allows entering dates using the the Hebrew calendar, with the suffix HE, for example:
20 Csh 5636 HE
The abbreviations for the month names are: Nsn, Iyr, Svn, Tmz, Aav, Ell, Tsh, Csh, Ksl, Tvt, Shv, Adr, Ads
The HE is optional, Hebrew dates can be recognised by the month names.
Technical Note: Hebrew Calendar dates are imported/exported to GEDCOM with the @#DHEBREW@ (HEBREW in version 7).