For those interested or for those that like using the terminal on a Mac
I recently asked this question when I found a strange file on my computer whilst trying to come up with the answer to the same question posed by this thread.
First, install homebrew through the terminal with this
ruby -e "$(curl -fsSL https://raw.github.com/Homebrew/homebrew/go/install)"
And then install djvu2pdf, which, by the way, has almost no documentation but works like a charm.
brew install djvu2pdf
Then, navigate to the directory where my .djvu file is stored, and run this command:
Since most textbooks have really long names that have spaces in between them, just enter a little bit of the name (enough to make it so there is only one file in the directory that starts with the current string) and then press tab.
It takes a while, how long I didn't figure out, but definitely not more than half an hour, and it will place a new file in the directory that is a pdf version of the .djvu file.
This is the only method I've found to work.