After a long silence, the riddles are back:
How can one legally enter Croatia through the city of Zagreb, which is not on the country border?
The answer I thought of was “by plane”, as Freemind correctly said. By landing in the Zagreb airport one can legally indicate “Zagreb” as the point of entry in the country.
I must admit I haven’t thought of IRC, but it’s not a physical means of transportation, unless you’re a mad scientist ;)