It is possible, although not pleasant, install Red Hat with the RULE installers fetching the packages over a serial cable. Specifically, there are no real plans to support this kind of install.
First of all, on the computer hosting the files, you must have set up an httpd server to listen on the port attached to the serial interface. In the second place, you must have connected the two computer with a null modem cable. After that, and after you have booted the target computer with the slinky disks, you must bring up the serial interface on both machines. On the server:
slattach -p slip -s 19200 /dev/ttyS1 & ifconfig sl0 192.168.1.1 pointopoint 192.168.1.2 up
On the target machine (busybox uses an older ifconfig…):
insmod slhc.o # load kernel module ./slattach -p slip -s 19200 /dev/ttyS0 & ifconfig sl0 192.168.1.2 dstaddr 192.168.1.1
More details of an actually performed installation over serial cable may be found at http:// mail.gnu.org/archive/html/rule-list/2002-05/msg00117.html