Don't think there's a specific guide as such. It's a very comprehensive program with a lot in it. Not really that hard to use, set you ip address, router ip (if you are using one) and PC ip address and that's you.
I don't use it because I feel it's too much. I use an ftp package and telnet and that's about it.
FTP - you can ftp images, plugins, etc to the /tmp folder and issue a command via telnet. You can flash using this method which is probably the quickest and most secure way of doing it. This is the way that most packages will flash the box but have their own GUI in front of it for ease of use.
If you want to backup your image you can use a telnet command then get the image file via ftp.
If you want to backup your services and bouquets use ftp to copy the /var/tuxbox/config/enigma folder or /var/tuxbox.config/zapit folder to your PC.
It's really whatever program you feel comfortable using. But sorry I don't think there's a guide for it on this forum, maybe someone else has one they could upload.