You don't have to...
If you downloaded it from
here, then you'll find a readme.txt which states:
Setting up firefox:
Make sure your browser have webgl open this link in firefox:
You must be registered to see the links
Type this in firefox adress bar:
about:config
Accept warning message
Search for the following and set it to false
security.fileuri.strict_origin_policy
Starting the game:
Open the game folder
Right click on index.html->Open With->Firefox
Then it should work.
Otherwise i could pack "my" versions (don't know where i found it) and load it up to .... let's see....