Edit: I also made a guide for downloading patch files as well: Downloading patch files outside of client (in-forum)
So this took me a while to figure out but hope it helps folks.
Having Notepad++ for quickly editing multiple lines and its find/replace regular expression functionality and a download manager capable of batch downloads is highly recommended here (Free Download Manager for PC / Advanced Download Manager for Android [if anyone has a suggestion for iOS feel free to comment])
Step 1: Let the launcher start up and do its thing until it starts to download files with .PAZ or .PAZ.tmp extensions at the end. At this point close the launcher.
Step 2: Open a new text file in your text editor. This will help keep track of URL stuff.
Step 3: Go to the Black Desert installation folder (was named BlackDesert for me) and look for a file named update.log. Open it in your text editor.
Step 4: Look for an INFO line that starts with CDN URL. Copy the URL and paste it in the first text file you made. Add /client to the end of the URL. Leave all files open so far.
Step 5: Go back to the BD installation folder and look for a file named install_version. Open it in your text editor, copy the number inside of it (should just be one), and paste that number to the end of the URL in your first text file. Then add /Paz to the end of that. The URL should look something like this now: http://naeu-o-dn.playblackdesert.com/UploadData/client/2142/Paz.
Step 6: Now go back to the update.log file and look for lines that say something like "failed to open pack: Paz/PAD00000.PAZ". Select the whole first line that says this (probably will be after a "building file-list to update" message) and select all lines until the last line that says that (should be continuous the whole way through), probably ending before a "downloading files" message. Copy those lines. Yes all of them.
Step 7: Go back to the text file with the client URL (your first text file). Make sure to start on a new line and paste your copied lines into the document. So now you should have something like:
2023-03-05 16:43:40 [INFO ] failed to open pack: Paz/PAD00026.PAZ
2023-03-05 16:43:40 [INFO ] failed to open pack: Paz/PAD00027.PAZ
The following few steps assume use of Notepad++; basically the point is to attach your pieced together CDN URL to each Paz/PADXXXXX.PAZ file.
Step 8: In the same text file (the one with all the pasted paz lines), press Ctrl+F to open the Find/Replace window. Go to the Replace tab and be sure to select the "Regular Expression" and "Wrap Around" options, and de-select the ". matches newline" option.
Step 9: In the Find text box, type .*pack: Paz (there is a period before the asterisk). This should select (on one line) everything from the beginning of that line to the end of the first Paz (not the second PAZ extension). Click "Find Next" to verify this is true and if not check correct options are selected/de-selected and the search text is typed correctly.
Step 10: In the Replace text box, paste the pieced-together CDN URL (something like http://naeu-o-dn.playblackdesert.com/UploadData/client/2142/Paz). Clicking "Replace" should result in one of the lines to be a complete URL such as http://naeu-o-dn.playblackdesert.com/UploadData/client/2142/Paz/PAD03233.PAZ. If this is not the case, ensure typing errors such as extra slashes haven't snuck in; otherwise, go ahead and click "Replace All" to replace the rest of the lines. The text file should now look something like:
Step 11: Now go ahead and remove the now-incomplete CDN URL (something like http://naeu-o-dn.playblackdesert.com/UploadData/client/2142/Paz) from the top of the text file. There should be no extra line/space at the top of the document for the sake of certain download managers. For Free Download Manager and Advanced Download Manager you can save your text file as a normal text file (though ADM will want a file named ADM.txt) for their batch downloading parts and it should be good to go to start the downloading process.
Step 12: Whenever the downloads finish, move the Paz files to the Paz folder in the Black Desert installation folder (should be something like BlackDesert\Paz\). Then reopen the launcher and it should do its thing. At the time of writing I'm still on the downloading part so will be a little bit before this part is definitive.
Anyways hope it helps to get people started!
Edit: After finishing step 12 everything worked well! I was not able to find a way to get the launcher to recognize any preloaded binary files that it first downloads before the big .paz files so one does have to let the launcher download those binary files itself.