I've never seen anyone use that Linux for mining. I'm not saying you shouldn't or that it's not possible...just that I've never seen it. The most common Linux distros I see used here are Xubuntu and Ubuntu. I use those, Crunchbang, and Mint. They're all related to Ubuntu.
My guess is that PClinuxOS doesn't have a "sudo" group. I don't have experience with Linux versions that don't have this feature, so the following advise may be shaky.You can try running the commands without "sudo", or running the commands as root. If you run the commands as root, you'll need to adjust the commands, i.e.,
usermod -G plugdev -a username
...where username is the name of the user that will be mining (usually not "root")