As you found out, the method is called "importStyles" not "importStyle".
One approach is to use the "properties" property to transfer the essentials of any native object.
Sub-objects such as the various settings and and options of object styles require extra steps, though.
myStyle.properties = otherStyle.properties;
You can also create a blank document, import the styles there and remove the non desired ones.
To keep connection with "Styles" I was looking for StylesRange option. InDesign UI is able to do it, since there are checkboxes in import window, thats why. If there is no script method way - thats OK. I just asked more experienced people before I step into monk room.