Plaster walls also have studs. The studs will be more difficult to find. On top of the studs you will have lath, which are horizontally mounted boards with some space between them. You might be able to use anchors but I recommend finding the studs.
Here is how I find studs: first I knock on the wall and note the tone. The pitch is higher for where the stud is located and you have less of an echo. My method is better than any kind of stud finder. Once you think you have located a stud, use a small 1/16 inch to 1/8 drill and drill into the wall about every half inch until you hit a stud. Plaster and drywall repairs very easily.
use anchors and you will only need one large lag bolt going into a stud, it should hold very well.