Hi Sebastien,
As mentioned in the earlier discussions OrgChart Analytics, custom analytics involves creating/modifying quite a number of xmls. However it can be achieved if you follow the existing standard analytics like Gender, Nationality, Disability etc.
I have developed a custom analytic as exactly as the other standard analytics.
You got to start with creating a file in OTF Schema in Appresources/OTFSchema/FunctionConfiguration for Live RFC and Analytics/Counts and SAPExtractor Function Configuration & Join Configurations files for Staged.
Next step would be creating dataelements like KPIElement, KPIElementLive, KPIElementStaged for details and views.
Later you have to create files in detailconfiguration, detaildataconfiguration, reportconfiguration, viewconfiguration etc.
As you may want to include your custom analytics in Demographic you may need to modify the files Demographicsorgunitdetails in detailspresentationconfiguration, demographicsorgunittabledetailspresentation and childorgunitdetails in detailconfiguration.
Please take any existing standard analytic as a reference and try the above provided steps.
Hope this answer helps.
Thanks,
Manohar