it's not able to set on enterprise edition.
2 ways to know number of cores used:
1) ps -ef|grep litespeed|wc
in your case(4-CPU license), it'll be 5. including the parent litespeed process (running as root)
2)check number of /tmp/lshttpd/.rtreport*
1-CPU is 1, 2-CPU is 2, 4-CPU is 4. i.e., one...