I don't really understand, but since the link is just a shell script you must be able to use it.
I do not know if it can work with the nautilus of gnome 3, but I think the following should work (not tested):
1. download the script, and save it into the directory where your cue file is.
2. open a termial, cd to the directory, and run the script with the cue file as arguent.
cd <the directory>
chmod +x "Split Lossless"
./Split\ Lossless <cue file>
The big point is the script may complain for dependencies. Install them using yum.