I do know if I make a group node of the nodes I want could do this. But is there a better way? Copy-Paste? (Note: I am talking about compositing nodes, not material nodes)
File -> Append -> select your file -> NodeTree -> choose the node group you want.
The same method works for all kinds of data (shaders, meshes, etc.).
EDIT: I just reread your question and realized that for whatever reason you don't want to group the nodes. I think my solution only works for a group of nodes. I don't know if there's a way to do it without grouping them.