Thanks for the link.
I've used /usr/bin/dbus-monitor to look at D-Bus events. It turned out that there is no CM destination implementation in current telepathy (Maemo 5). And it looks like you'll have to send the D-Bus message to each account you have in telepathy separately.
To do that, I guess, I need to read D-Bus manuals first... It's not that intuitive as I want it to be. Anyway, I'll keep you updated as soon as I'll figure out how this thing works.