Hi,
The steps would be:
1. Set a meetme number range from ccmadmin feature>meetme
2. from an ip phone pickup the handset, press the meetme softkey and dial the nuber, that starts the meetme conference (has to be an ip phone.
3. Others can join by dialing the number only without the softkey.
more info is available at:
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_administration_guide_chapter09186a00803ed6bb.html
HTH, Avner.