Therefore, I present - Apollo
This tool makes the following changes to any given PKZIP-compressed XPI or JAR file:
- Replaces version numbers for ec8030f7-c20a-464f-9b0e-13a3a9e97384 entries with the range 0.* - 9999.* in install.rdf files.
- Removes appversion from ec8030f7-c20a-464f-9b0e-13a3a9e97384 rows in chrome.manifest files.
- Replaces ec8030f7-c20a-464f-9b0e-13a3a9e97384 with 8de7fcbb-c55c-4fbe-bfc5-fc555c87dbc4 in all files.
- Removes files in the META-INF folder (digital signature data) if present.
This tool is solely for personal use - do not redistribute Apollo-modified XPI or JAR files as though they're supported, maintained add-ons under any circumstances. You can use it to quickly make the changes listed above, but it's a virtual certainty that more work is, and will be, needed. A big part of the reason the version range was set to such an impossible value is to encourage you to modify the add-on yourself, and discourage redistribution.
Disclaimer: Apollo is a very bad idea. Using it is a bad idea. Using extensions generated by Apollo is a bad idea. Using themes or localizations generated by Apollo is an even worse idea. So if you break your browser's profile, installation, your operating system, or your entire computer, you only have yourself to blame.