From what I've studied, you can't. Ley lines aren't static; they are an electromagnetic phenomenon that is likely generated by the earth's core. They are constantly oscillating back and forth like guitar strings, so the only real way to capitalize on their power is to go to one of the "nodes," where multiple lines converge. That appears to be the only "static" spot that you can reliably go to if you knew where it was on a map. However, even these will drift over the years and change locations as ancient temples and templar churches that were built on these nodes are no longer relevant; when measured, it can be observed that the node has moved outside the area of the temple/church to be in a courtyard or a fountain nearby.
Even if you don't have an accurate map, if there is an ancient site of worship in your area, there is a good chance it was built on one of these nodes. Temples, pyramids, and the like were all built on these.