Implementing ME side seems relatively easy, but I could find a way to communicate with SIM. Communication between ME and SIM is described in http://www.3gpp.org/FTP/Specs/html-info/1114.htm

Usually SIM access is done through Dbus, but I found only methods for reading IMEI and accessing contacts on SIM.

http://wiki.maemo.org/Phone_control
http://mxr.maemo.org/fremantle-20091...y-maemo.c#1815

I could not find code for service(s) that replies to these DBus messages and actually accesses the SIM card.