The IM only desktop share has been released on the full Jabber for Windows client, since about release 11.0, see snippet below from the Cisco Jabber 11.0 Planning guide. As you can see this is only windows to windows IM initiated desktop share and not Windows to Macintosh.
I have not seen any indication that the Jabber API's have any more functionality on this than the full client/server setup. So all in all you might be able to find the windows to windows IM based desktop sharing within the SDK, but I seriously doubt it, seeing that this feature has not been around on a lot of Cisco Jabber versions yet.
IM Only Screen Share
Applies to Cisco Jabber for Windows.
IM Only screen share is a one to one screen share and is enabled using the EnableP2PDesktopShare parameter in the jabber-config.xml file. In a chat window users select ... > Share screen.
The port range for this option is 49152 to 65535 and this can be reduced by using the SharePortRangeStart and SharePortRangeSize parameters in the jabber-config.xml file.