You're referring to Red Hat version 8.0, running a 2.4-series kernel?? That version was end-of-life back in 2003 or 2004. I don't believe the realtime scheduling policies are available in any kernel prior to 2.6.x, based on the link provided in the first comment on the post.
Edit: The kernel in use is actually a 2.6.x kernel. The command needed to make this work is
chrt. In this case, it will need to be backported or compiled from scratch for the Red Hat 8.0 server. I suspect you'll run into other issues doing so, but for anyone else who stumbles upon this,
chrt allows this.
From the man page:
chrt - manipulate real-time attributes of a process
chrt [options] [prio] [pid | command [arg]...]
chrt(1) sets or retrieves the real-time scheduling attributes of an existing PID or runs COMMAND
with the given attributes. Both policy (one of SCHED_OTHER, SCHED_FIFO, SCHED_RR, or
SCHED_BATCH) and priority can be set and retrieved.
A real example:
# Set JSINIT processes for e-commerce to FIFO scheduler and realtime priority 75.
for i in `pgrep -f 'JSINIT\ I.*' | xargs`; do chrt -p -f 75 $i; done