jQuery bookmarklet for selectors

Question

It should work like this:

1. Fire a bookmarklet
2. Select the first element by clicking
3. Select the second element
4. It outputs a series of jQuery calls which would allow selecting the second element given a reference to a first element (i.e. using relative positions of the two elements in a DOM tree).

Is there such a bookmarklet (or browser extension)? If no may be you could give me a clue about how to write one?