Applying for G4 Visa - Need to Be in Home Country

Hi all. I'm currently living in the US on an L1 visa. I will soon be starting a new job that will be on a G4 visa. I know I need to leave the US to be able to make the change (apply for the G4). However, I have not been able to find out whether I *have* to go to my home country (UK) to do so, or whether I can do so at some other US embassy/consulate.

I am also planning to make a trip to Latin America for some Spanish Language tuition before starting the new job - if I could kill two birds with one stone and apply for the G4 visa over there, that would be a great help.

Any advice would be very much appreciated. Thanks all.

An interview is not required for a G4 visa.