beside dbus there is also a tool called mc-tool i think. Its part of the osso-mission-control package and can be used to setup, modify or manage the IM accounts. No idea if it's supported to be used in any way, on n800 I used it to set a dedicated network interface for a sip account (tun0 instead of wlan0). On n900 i had it installed but only used it to list the configured accounts up to now. Unfortunately i just had to reflash my n900, so i can't test if it can be used to actually change the status.