Change / Remove keyboard shortcut in Lotus (IBM) Sametime

Question

I am required to use the Sametime communicator on Windows 7 and, unfortunately, I am used to a non-standard keyboard mapping that requires me to insert some letters from my native language using not so common keyboard combinations. Basically, AltGr + s = ș and AltGr + t = ț. By default, pressing AltGr + s in the Sametime window opens the context menu and pressing AltGr + t changes the focus from the text box, which is driving me insane.

So far, I tried to look in the gazillions of settings and in the installation folders for some configuration file, but no luck. Is there any way to remove these silly mappings? I'm even considering writing a plugin for it, if their API provides a way to intercept key strokes...

Thanks in advance!

PS: No, I am not allowed to install some software, such as AutoHotkey, in order to fix it...