You can do it from MENU > SYSTEM > VASMCC > X WINDOW > KEYBOARD SETUP.
But I think the better way to do this is editing the xorg.conf file directly. If you want to do that:
Open a console and login as root with the su command
Then with the text editor of your choice open the /etc/X11/xorg.conf, for example:
# medit /etc/X11/xorg.conf
Find a section looking like this:
Option "XkbLayout" "es" ## KEYBOARD_MAP!
Option "XkbModel" "pc105" ## KEYBOARD_MODEL!
Option "Xkbvariant" "" ## KEYBOARD_VARIANT!
Change "XkbLayout" "es" to "XkbLayout" "pt_PT" or "pt_BR" or whatever you need, for a complete list of the options and variants for the pt layout type locale -a | grep pt in a console. Save the file, close all your apps and restart the X server with CTL+ALT+BACK.