The tools are unfortunately outdated, but not necessary for variant development. I am pretty sure, that most of the variants on vdip are created without their help.
The guide that kaner posted focuses on the creation of the map png files which is the biggest part of work for variants, that only change maps.
Another (outdated) guide by Oli himself goes a bit further and gives a complete overview of the creation process. It can be found here: http://forum.webdiplomacy.net/viewtopic.php?f=25&t=432. However, there is nowadays a useful tool for entering the raw data into the database. For that I recommend the lab.diplomail.ru, which acts as a replacement of the old website for developing variant, lab.diplomacy.com. If you contact the admin Flame over there with your variant files, he will probably install them for you so you can use the Edit-Tool for entering the territory data into the database.
For additional rules, things get a bit more complicated. For existing rules, it is mostly just copy and paste the code from other variants that use that rule. However, as long as there is no detailed guide on that, I recommend some basic knowledge in php so you know what you are doing and get a satisfying result.
Unfortunately we have lost detailed guides on variant creation with the disappearing of a vdip-wiki due to technical issues some time ago. I am still hoping, that the data can be recovered at some point.
For the further progress after the variant is done and tested, I cannot give much advice. In former days when Oli was very actively administrating the website and things were developed on his lab, finished variants just got ported over here when they were finished (and I am not aware of unpopular variants being removed again). Some even got installed on other webdip installations.
However, it has been a long time since the last variant got installed over here and I am not aware of the current state. But since Oli seems to be returning to website, there is probably no big deal with installing a finally finished variant on this website.