setxkbmap allows to set multiple keyboard layout together with a switching mechanism. The Archlinux-wiki Write provides excellent information about this subject.
For example, making the US-American and the Swiss keyboard layout available and having Alt+Caps switch between them, the following is written into '~/.X.d/setxkbmap'.
setxkbmap us,ch -option grp:alt_caps_toggle
The same can be achieved by use of a Xorg-configuration file as described in a forum entry.
LXDE does provide its own mechanism for handling keyboard lay-outs, making the above procedure unnecessary.