On my system, I have 96MB of memory. Using the following boot command with the Fedora Core 1 CD worked for me:
linux text askmethod mem=exactmap mem=640K@0 mem=95M@1M
Note that Fedora Core 2 (which uses the 2.6 kernel) did not work with this map at all and locked the machine up rather tightly.
Give this a shot, good luck.