Yes, it is available in CME, see user guide:
Swap Between Held and Active Calls on Multiple Lines
If your phone supports multiple lines, use line buttons to swap between held and active calls.
For example, if you have a held call on Line 1 and an active call on Line 2, press the Line 1 button to make the Line 1 call active (resume it from hold) and to automatically put the Line 2 call on hold.
http://www.cisco.com/en/US/partner/docs/voice_ip_comm/cuipph/6921_6941_6961/8_6/english/user_guide/callfeat.html
HTH,
Chris