I have went through the trouble of installing Congress Country Club manually, and I thought I should share the steps it took, in case some of you find it useful
Thanks madve2! I followed these instructions for the Davis Love III / Sea Island CD, and thought I'd post the resulting regedit file as well. The course and resort seem to load, but you can't play as Davis Love III the same way you can pick Arnold Palmer - I'm not sure what's missing/wrong.
Windows Registry Editor Version 5.00
[HKEY_CURRENT_USER\SOFTWARE\Access\Links LS 1998\Options\&Davis Love III/Sea Island]
"TourCD"="Sea Island CD"
"Title"="&Davis Love III/Sea Island"
[HKEY_CURRENT_USER\SOFTWARE\Access\Links LS 1998\CRX\Course25]
"Name"="Sea Island Golf Club"
"CDTitle"="Sea Island Course CD"
"Tour"="&Davis Love III/Sea Island"
[HKEY_CURRENT_USER\SOFTWARE\Access\Links LS 1998\Options\Tour Players]
"20"="&Davis Love III/Sea Island"
You're welcome, I'm glad you found my post useful!
Indeed the Davis Love CD is the one that caused me the most trouble as well :) (I've got my hands on it after I've written my previous post.) The problem being, that one of the files that the game needs for the player animations cannot be found on the disc as-is; it looks like it is generated as part of the installation process (similar to how the import process for Links 386 courses work I guess). Therefore you can't (or at least I wasn't able to) make it work with simple copy-pasting and registry editing. (Which is weird because basically anything else I've tried works that way – some CDs have 3D "virtual tours", and those work by copy-pasting too.)
In the end, I used a virtual machine and an original Links LS base game to install the add-on CD "properly", and then grabbed the missing file (DAVISIII.ani) out of the virtual machine for use with the GOG version.
All in all, you need these 3 files (and no registry changes):
1. Copy DAVIS30.LS from the ANI folder on the CD into the ANI folder inside the game directory
2. Copy DAVISYJA6.pin from the CD root into the game directory root
3. Copy DAVISIII.ani (not on the CD, as mentioned above) into the ANI folder inside the game directory
If you don't want to go through the virtual machine method for obtaining the last file, this link should work as well: https://www.mediafire.com/file/6igj6yexfqxvybg/DAVISIII.ANI/file