Ignore most of it for now. Look at the right-hand menu. You need the instructions and the unlocked images. (IIRC there is a "locked" version in the zip file as well in case you need it. I haven't heard of any unlocking failures though).
Once you've unlocked it you can use the xdslcmd commands through telnet, but I strongly recommend the Bald-Eagle1 scripts for ongoing logging, and graphing as required.
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.
The ECI modem, also sometimes supplied as part of a FTTC installation can also be unlocked, but not as easily as the HG612 & reliable graphing/data harvesting scripts and/or programs are not fully developed for that model yet.
The HG610 f/w was never locked. Both Chinese and English f/w allow full web and telnet access.
if the HG612 f/w is flashed into the HG610 its two extra ethernet ports will disappear, and a few config options will disappear.
Which reminds, it would be good to know if the HG610 f/w works okay in all circumstances in the HG612.
Not that there's much to gain, except the ability to save the current configuration.