Note that the Scripts Document Class is a custom class I created by Going to Configure/Preferences window and clicking on Document Classes... you can only create a new Document Class while NO DOCUMENTS ARE OPEN, as it says. Other aspects of the Scripts Document Class can also be configured - like looking for .grg files and having line numbers visible.
IMPORTANT: Where to put the syntax (.syn) file so TextPad can find it? Well, I am using XP and the following path leads to a folder where you should put it with all the other syntax files. If you are using Windows 7, then you will have to figure out the path yourself - look for the Helios/TextPad/7 application subfolder, I think.
C:\Documents and Settings\your username here\Application Data\Helios\TextPad\7
You can use TextPad, itself, to update the syntax file as more commands are added in the future. No guarantees that ALL commands are in this version of the syntax file which I maintain for my personal use ONLY.

Sven