These instructions as posted by fratveno in this thread work:
Dorico will compute the GUID number. But it takes the steps as outlined below. I’ve duplicated those steps here:
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- Copy the name of the plugin faithfully (without the extension) and put it into its own line in the WHITELIST file. Then put 32 zeros on the line beneath it. The plugin itself will have to reside in one of the default paths. (there is an xml file listing those as well - install a reader that formats xml in a digestive way, e.g. (equivalent to) notepad2 on windows)
- Start Dorico and quit again immediately. The xml files will get updated.
- Open the defaults.xml file and look for the line with 32 alphanumeric charachters ending in “=0”. That will be your plugin. Change the “0” to “1” and copy those 32 glyphs (the GUID) to the clipboard and save the file. If there is no such line ending in “0” then your plugin has not passed the verification.
- Open the WHITELIST file again and replace the line with 32 zeros with the GUID from the clipboard. SAVE.
- Launch Dorico and your plugin should be available.