If I'm positive for (ebv) should I get a polio vaccine to work as an emt? Or could there be a way around that?

Yes. If getting the polio vaccine is a requirement of work i see no reason not to get it if you are positive for epstein barr virus. Most adults are ebv positive. Most adults vaccinated for polio as kids don't require vaccination in adulthood. Some require it because of occupational exposure or chronic disease. The vaccine you will be getting is the ipv. It is not a live virus and is a mild vaccine.
Get all immunization. You should get all your immunizations up to date to work as an EMT, since you will potentially be exposed to the variety of infections.
One polio booster. For adults, the recommendation is 1 polio booster shot for people with higher risk of exposure (the shot is not alive, compared to the oral vaccine that is a live virus). Nobody wants to catch polio, which can paralyze you for life. Ebv is very common, and many people have caught it by adulthood. Having ebv is not related to whether or not a person should get any of the usual vaccinations.