There are two main approaches you may want to consider:
- Server-side. This approach would use the Presence Web Services APIs (REST or SOAP) into the IM&P server to register and manage presence on-behalf-of users. A custom application would use the Presence Web Services to manage user presence, exposing its own APIs or otherwise interacting with browser (or native/mobile) application to propogate presence information outward.
Note the latter - Presence Web Services APis - do not support IM. For IM integrations not in-browser you would need to use the XMPP protocol, e.g. using various 3rd party XMPP stacks and libraries (Cisco does not recommend any particular flavor.)
Further note: these are development building-blocks, and as such there is no simple prescriptive step-by-step instructions for just 'deploying' them. Developers will need to explore the APIs and architectures, decide how best to incorporate or extend into existing solutions (e.g. Sharepoint) and perform significant coding/testing work to achieve a complete integration.