Hi mate,
On the JTD its in the same place as the other MK2 Puntos. AT the bottom of the fusebox to the right of your knee (Uk car)
The JTD is not fully OBD2 compliant, so you will need to chose your diagnostic software carefully, otherwise you will be limited as to being able to read fault codes etc.
HOWEVER, FiatECU Scan and a VAG Com cable will work 100% with the JTD. UniDiag and a VAG Com cable will also work.
Hope that helps,
Alan