We have CIC 3.0 SU16 and we are currently using MAPI connector to Exchange. I am looking for some documentation to enable Exchange Web Services in CIC. Can anyone help please? We have impersonation setup already on exchange side.

Save yourself a lot of time by testing Exchange first. Use www.testexchangeconnectivity.com and download EWS Editor. These will test and confirm your impersonation settings. Then you can try to use the same settings in the Mail container. Change a mailbox to use EWS and test. If 3 green checks, you are good. There is a utility that can migrate all your boxes over.

I don't know if you have access to the Support web site, my.inin.com, but there is a Knowledge Base article that walks you through migrating from MAPI to EWS in 3.0 SU15 and later (4.0 SU2 and later) https://my.inin.com/Support/Pages/KB-Details.aspx?EntryID=Q134211742300663