Hello,
You don't say which Zaurus you have, or if you have any kind of network connection. You'll find all the info you need by searching the forums.
As a pointer for what to search for, you'll probably need to format your SD card with an ext2 filesystem, and then just run package manager, point it at the ipk files you downloaded, and when it asks, tell it to install to SD.
I'm pretty sure there is a discussion about this somewhere on here ...
Good luck,
Mike.