Yes, I do. In typical "Ryaurezh" fashion, the problem practically sorted itself out AFTER I posted my question. I decided to try hitting the "Install" button for the mods. Fortunately, the launcher detected them, so it didn't need to redownload. Then I went back into the installedpacks file, and entered the information for my custom pack. Somehow, it worked just fine that time.
I tried to install a custom offline modpack, and added it to the installedpacks file. Now I get an error saying that it is unable to load the file, so it wipes it clean and none of the mods I have installed are listed. I didn't make a backup of the original file, but I did reconstruct it based on the original mods I had installed and it does the same thing. How can I 1) restore my mods without reinstalling them, and 2) add a custom modpack to the launcher without uploading it?