For a fedora/rhel specific solution, you could create a fedora netboot CD by re-packing the isolinux directory as a bootable CD with mkisofs, while changin the isolinux.cfg file to start a VNC installation by default
You should edit the isolinux/isolinux.cfg and add "vnc" to the append directive of the default boot stanza, usually something like this:
label linux
kernel vmlinuz
append initrd=initrd.img ramdisk_size=8192
would turn into:
label linux
kernel vmlinuz
append initrd=initrd.img ramdisk_size=8192 vnc
you could also add ip=(ip) or ip=dhcp and method=(http|ftp|nfs):// (or whatever you have) so the installer gets a default/dhcp ip address and can find the network installation sources faster
edit: forgot to mention that using a static ip would be easier, 'cause then you know to where to connect with a vnc client