newbie - modules for jython (under grinder 3) ?

[bugbear]

I'm just trying to use Grinder 3 to beat
up my http-app.

Grinder 3 comes with its own jython.jar.

Some of the sample scripts:
http://grinder.sourceforge.net/g3/script-gallery.html
use import statements that don't work for me.

Reading around, these are reference to modules.

Do I need a "proper" jython instead of the one
that grinder ships with?

Or...

Do I need to get and install some modules?

If the latter, where from and how?
I note that not all Python modules
can be used as Jython modules.

My most urgent need is for the threading module, although
I've faked my way round that by using Doug Lea's
concurrent library in java, which I can call
from Jython.
http://gee.cs.oswego.edu/dl/classes/EDU/oswego/cs/dl/util/concurrent/intro.html

But I'd like to know how to do it "right"

    BugBear