You can modify IP addressing on Fedora 10 either through the GUI by System | Administration | Network or through a terminal by system-config-network . Unfortunately, my experience is something is broken when not using DHCP.
I found the subnet mask being set the same as the IP address, found the subnet mask being set to 32 bits, and found DNS servers not being retained after network, NetworkManager or server restarts.
Ultimately I edited /etc/sysconfig/networking/devices/ifcfg-eth0 by hand and all seems to be well. Mine ultimately looks like so:
# Intel Corporation 82801BA/BAM/CA/CAM Ethernet Controller
This survives service network restart, service NetworkManager restart, and server reboots, but I imagine it is the only trustworthy method of modifying the IP adressing.