This simple guide is intended for Ubuntu 7.04 (Feisty) users, but may work for other releases as well.
To get moto4lin to work right, you'll also need the p2kmoto package, but for some reason the Ubuntu guys put moto4lin in their repositories, but not p2kmoto. I noticed there's a source package in Gusty (7.10), but no .deb. So, here's how to get it quickly working on your system if you don't want to bother compiling it.
$ sudo apt-get install moto4lin
After installing this package you will need to download the .deb for p2kmoto from somewhere. A quick Google search found the following sources for me:
(this last one seemed to stall out for me, but might work for you)
Now of course, I can not vouch for either one of these sources, so download at your own risk!
Once you have installed both moto4lin and p2kmoto, you (in theory) should be able to just type in:
$ sudo moto4lin
However, this did not ever work right for me... Instead I had to run the p2ktest program first, and then moto4lin worked after that. Also note there are ways to change your udev rules so you don't have to run this app as root, but as long as you're careful you should be fine running it with sudo, as listed above.
It's still not perfect, and a little slow seeming to me, but it gets the job done...and for free! Those bastards at "the new AT&T" wanted to charge me $50 for a cable and some crappy software CD (most likely Windows only anyway). A handy little $15 multi-tip USB cable set and some good ol' open source software just seemed like the better option to me ;)