The laptop was your typical 486 laptop with PCMCIA slots, a floppy drive, an internal 14.4k modem, and a 250mb hard disk. There are lots of options here, though only three really realistic ones: Installing the Debian distribution of Linux over FTP, doing the entire installation with floppies, or installing it over the network. Having not installed Debian before and not desiring a floppy installation, I went with the Network installation. I already have two machines capable of running Linux, and one has a CD-Rom on it. I happen to have a copy of Slackware Linux on CD (albeit an older version than the current one), so this seemed to be the best option. I had to make a couple of floppy disks to boot the system up and I was able to get the system to boot okay.
My first problem was in getting the system to recognize the network card with the installation floppies. I figured it might have had something to do with using an older version of the boot disks, so I went and checked for an updated Slackware release and found that I was two revisions out of date. I Downloaded the latest and greatest boot disks and the system was able to recognize the network card. From there, it was a matter of walking thru the installation process and asking Fred what he wanted installed. After a few more reboots and bit more reconfiguring, we got his system so that it could dial up to the Internet and recognize the PCMCIA network card from the Linux installed on his hard disk.
At the end of it, we had a portable Unix machine that could dial up to the Internet, browse the web, develop software in C and Perl, and even serve up web pages. All with about 120 megabytes left on the hard drive. ;-)
Of course, for a geek like me, doing this kind of stuff is old hat. For the rest of you, the task may be daunting. If you're new to the Linux thing, I would go out and get a distribution of Linux on CD. I've seen them as cheap as $12 at some of the local computer stores. Most of them come with a manual that will help you install Linux correctly. To get a good idea of what's involved before you waste your time, check out the "HowTo" document on Installing Linux.