Where can i hookup boost gauge on 1.9jtd

Two options I guess - easy option is to buy a bluetooth to OBD2 adapter and download AlfaOBD for your smart phone. You can choose a range of style & size gauge that will run directly off your MAP sensor. Then get one of those windscreen suction cup phone mounts and you're sorted. When you're carrying your gran about or whatever you can remove it.

More difficult & expensive option would be a physical gauge and It seems like that's what your asking. In my opinion I would remove the EGR valve and drill and tap that. While you're there it's a chance to clean it out and remove any swarf etc you produce. Plus it's a small part so easy to hold in a vice.

Or do this:

https://www.fiatforum.com/members-motors/333043-smurf-toad.html

See the 8th, 9th and 10th photos down in the first post.