The KDE desktop has a program kxkb. I am looking for a program that can be used on a system with only MWM installed as a window manager.
Is there such a graphical user interface for Motif based systems?

The kxkb program is configured through the KDE Control Center Application to be able to click on a language abbreviation so to change the keyboard layout as well as what UTF-8 characters appear when a key is pressed. It behaves much like the Microsoft (R) Windows XP (TM) multinationalization feature. (The way that KDE and Microsoft do it is quite nice -- but Microsoft's way of doing it is even better because it intergrates with the osk.exe program (On Screen Keyboard).)

While using the kxkb program I am able to input via typing into the XmText and XmTextField the UTF-8 encoded characters for any language unicode supports. (They can be entered, but whether Motif can render them using the fonts in a default Linux (TM) or Unix (TM) install is quite another matter, but that's a different subject altogether. I have a post about this in features requested for Open Motif 2.4+.)