Because people seem to be poking GM script writers a lot more often to convince them to include KoLmafia relay browser support, I decided to save everyone time and modify Greasemonkey itself to provide that support automatically. So, if you trust the modified source code enough (I added maybe 12 lines to greasemonkey.js in the components folder in the Greasemonkey source code), you're more than welcome to install the modifications.
To do so, download the attached file to your desktop. Then, drag and drop the downloaded XPI into Firefox (if it's attached as a ZIP, simply rename it to XPI after downloading). This will prompt you for installation. After installing the add-on and restarting Firefox, all Greasemonkey scripts that were only injected into KoL pages should now also be injected into KoLmafia's relay browser.
There is, however, one caveat: the relay browser pages will not be explicitly listed in the include pages. This is to leave it clear that the scripts do not necessarily handle KoLmafia's injections, or even KoLmafia's need to have the port be explicit. Therefore, because they were not intended to be included in KoLmafia's relay browser, you should under no circumstances bother the script writer about their script not working under KoLmafia.