Plaster is a mess when you cut it by mechanical means. No matter how good you seal stuff up the dust will get all over the house.
Go get a one time use cheap wide wood chisel. Take your time and cut where you need to. Crack the remaining plaster with a hammer and put it bags or boxes immediately.
Then use a small saws all to cut the lath and pry it off with your claw hammer. If you go nuts just smashing plaster and lath you will have a mess to clean up that will take quite a long time. Be neat about removing it and you will save allot of time in the long run.
Take your time and be clean.
Use a drop cloth, break the plaster off the lath first, and clean it up.
Then just pry the lath off and bundle it up.
thanks for the insight gentlemen. this is going to be tough then...i am not worried about the mess as much because i am replacing the carpet afterwards, but i would like to contain dust as best as possible.