if you have a max star 150 or 200 you would do best to just use the dryer outlet as its likely to be the largest wire and breaker in the house. just stick to 120V. even if you don't burn down the house you will get thrown out of the building for even the slightest alteration to the power system. the jumper you ask about is just going to get you into trouble. buy a 120V capable welder and use it. although truth be told if any one finds out you are welding in the apartment you will likely be looking for a new place to live really fast. the Dyn 200 has been run up to 195 amp's on 120V power, i would suspect the max star (the DC only version) would act similarly. keeping in mind your duty cycle will be next to nil at that point. good luck to ya.

i agree 100% with the others about your attitude, a lil work there would go a long way to getting help. wile it may be true not many will bother to reach out and smack you over it, there is a lot of knowledge here to be had if you don't piss every one off. but its your bridge, burn it if you want.