RELUMP
From OHRRPGCE-Wiki
Lets you re-package an RPG file that you have manually unpacked.
There are two versions of RELUMP. A simple one which you can download here: http://hamsterrepublic.com/ohrrpgce/nightly/ohrrpgce-util.zip
There is also a windows-only version written in VB.NET by Mike Caron, which has a few extra options. Source code included. However, this is deprecated, and should not be used unless you have no other choice.