The automatic recording of calls by an agent can be done by creating a CAD Workflow in Desktop administrator.For more details refer to the Cisco Desktop Administrator User Guide..
http://www.cisco.com/univercd/cc/td/doc/product/voice/sw_ap_to/apps_4_0/english/agents/cda611ug.pdf
However, please note that the recording capability is targeted at an on demand usage (i.e., agent/supervisor pressing a button) and automated recording of specific call types (i.e., limited by filtering calls based on parameters such as called/calling number). The system is not sized to support a logging application which requires extensive disk storage and an archiving capability. The software protects the disk by deleting calls over a certain age and by not recording calls if the disk does not have sufficient space.