I believe so. If it is not downloading from the site automatically I think if you download the plugins and place them inside the Download folder at the root of your winbuilder folder then you will be able to install each plugin manually.
Go to the Plugins section on the forum downloads and download Win7PE and any other plugins. Drop them all into that Downloads folder.
Now in Winbuilder after you load your source... you will need to install each plugin. You will only need to type the first 3 characters of each plugin unless there are multiple Plugins with similar names... so for instance type...
This will install Win7PE, Gotcha Data Backup, 7-Zip, and AmmyyAdmin.
Although I think there is some other manual work you have to do for some of the plugins. It will give you that info in the command window though. I think there is a bug they are working on where some of the portable exe's do not expand automatically. So you may need to go online and download the portable exe and install it manually into the directory specified. For instance ClamWin needs to be downloaded and installed into the lib\plugins\AntiVir\PiriformClamWinPortable folder.
Once everything is ready... then type AUTO and it should build your Win7PE iso.
The new winbuilder is great. It is pretty easy once you have everything setup. It is being worked on to get some of the kinks out and more plugins will be made soon.