ja napot.
EUrail is ONLY for those who do not live In Europe.
INterRail is for those who do. It is valid on trains in nearly all countries of Europe, but in home country only for trip OUT and IN. It is all clearly expalined in the homepages.
IF this is the only trip you want to make (but not come back?) then its evident you do not need a pass for many days, just a single tripticket-this you can buy online from the railway in that country-ITalia= TrenItalia, till Ventimiglia, last stop before border FRance. Find their site and just try. the last short trip is only to buy in the station from a machine-these are local TER trains and run ev 30/60 mins all day.
I did not know that, sorry! Thank you for your help, I will try. :)