setterm is part of utils-linux-ng that has not been packaged.
If you want the man page for setterm it's in ncurses-man.tazpkg ;)

Thank you mojo for reply.

Sorry mojo, but I don't know how to change beep frequency with ncurses.
Do you know how to achieve with ncurses on real linux console an equivalent of
setterm -bfreq
For me it is impossible.

nano .xinitrc

xset b 30 550 300

volume
frequency
duration

Adjust the numbers as you please.

Logout/in to test new settings

Thank you mojo for taking your time. Sorry, but xset works only on x and x terminals. I use sometimes SliTaz without x server. Setterm works with real linux terminal and is really missing, because there are practical no tools for changing linux console behavior. Wanted to achieve this with changing terminfo entries, but tic is removed from kernel.

I asked too often, it's time for work. Created receipt for setterm. It is for stable. I have stable on my old ThinkPad, so for me testing is only possible on stable. As I'm Linux beginner this receipt may be buggy. Kindly request to all - verify it and make improvements. Somehow it works, even changes background on real terminal tty not pts in virtualbox. Soon test on real computer. Dear developers please consider adding setterm to cooking.

# SliTaz package receipt
PACKED_SIZE_"9.2k"
UNPACKED_SIZE="22.5k"
PACKAGE="util-linux-ng-setterm"
VERSION="2.16.1"
CATEGORY="base-system"
SHORT_DESC="The setterm utility from Util linux NG."
MAINTAINER="all@invited"
DEPENDS="glibc-base"
BUILD_DEPENDS="slitaz-toolchain"
WANTED="util-linux-ng"
WEB_SITE="http://kernel.org/~kzak/util-linux-ng/"

# Rules to gen a SliTaz package suitable for Tazpkg.
genpkg_rules()
{
	mkdir -p $fs/usr/bin
	cp -a $_pkg/usr/bin/setterm  $fs/usr/bin
}

And here the link to slitaz package for stable 3.0 http://dump.no/files/0e5b753b4145/util-linux-ng-setterm-2.16.1.tazpkg If you want to cook it on cooking change version to 2.18

Just changed system beep to guitar c on my 11 years old ThinkPadsetterm -bfreq 130 and it works, seems all is all right. By the way setterm -bfreq mutes annoying beep and is independent from x, works with kernel.
It works with /dev/ttyX only. On /dev/pts/X use xset. Check your current terminal name with commandtty

@Gawron
Run tazwok cook util-linux-ng in wok-stable
Copy/paste your receipt into a text file named receipt
Mkdir util-linux-ng-setterm in wok-stable
Mv receipt into util-linux-ng-setterm directory
Run tazwok genpkg util-linux-ng-setterm

http://www.mediafire.com/file/m73pwi5pds0du7k/util-linux-ng-setterm-2.16.1.tazpkg

Today Paul checked ad added this receipt to cooking.
The problem is solved.
Thanks Paul and mojo for help.