There should be no problem accessing the cm:destination property.
However cm:destination is on a type called cm:Link and that's probably more of a problem. Either a link will be pretending to be a file or folder over CMIS or it won't be shown at all.
The next version of Alfresco will have support for cmis item which can deal with types other than file/folder.
Thank you! In my case "won't be shown at all" seems to be true. I'm programming a GWT webapp to manage documents in an Alfresco Repository, and we used cm:destination to link *.doc files to generated pdfs. Now I want to switch repository access to CMIS (I used the webclient before) and the property just doesn't show.