you are supposed to post some other useful data to get help, you did not mention which card you have nor the output of lsmod ... :-)
try to configure wireless through Control Box, a configuration frontend that you can launch double clicking the PC icon you should have in the right corner of you lxpanel bar

To keep iso small no wireless modules.

root@slitaz: tazpkg get-install linux-wireless

If you have USB wireless:

root@slitaz: tazpkg get-install usbutils

Follow this: http://doc.slitaz.org/en:guides:wifi-easy

sorry mojo, i'm not going to post about wireless anymore :-)

I entered lspci -v | less into the terminal (in Ubuntu) and got this:

02:00.0 Network controller: Atheros Communications Inc. AR2427 Wireless Network Adapter (PCI-Express) (rev 01)
Subsystem: Device 1a3b:1112
Flags: bus master, fast devsel, latency 0, IRQ 17
Memory at fbff0000 (64-bit, non-prefetchable) [size=64K]
Capabilities:
Kernel driver in use: ath9k
Kernel modules: ath9k

In SliTaz I clicked on configure wireless -> drivers and tried to load the 'ath9k' module, but with no success. Wireless was still disabled.

The 'tazpkg...' command doesn't work without an internet connection.

if you have internet acces in another pc or in the same pc with another os you could download the required packages from here http://pkgs.slitaz.org/ and install then with tazpkg install instead of tazpkg get-install.
type tazpkg --help to see how it works