For positional parameters starting from the 5th one:
zshoryash.myCommand "${@[5,-1]}"
(note, as always, that the quotes above are important, or otherwise each element would be subject to split+glob in yash, or the empty elements removed in zsh).
ksh93,bashorzsh:myCommand "${@:5}"
(again, quotes important)
Bourne-like shells (includes all of the above shells)
(shift 4; myCommand "$@")
(using a subshell so the shift only happens there).
csh-like shells:
(shift 4; myCommand $argv:q)
(subshell)
fish:myCommand $argv[5..-1]rc:@{shift 4; myCommand $*}
(subshell)
rc/es:myCommand $*(`{seq 5 $#*})es:myCommand $*(5 ...)