If you are just trying to get some kind of extracted oil than includes urushiol (the active compound in poison ivy), then leaching pulverized or ground leaves with ethanol would work. Probably you would want to evaporate the ethanol afterwards to obtain an actual ‘oil’ rather than a solution or tincture.

If you need to actually obtain more or less pure urushiol without a bunch of other organic compounds, then you would need to do some further workup. Here’s one patent that suggests a method. Seems like a bit of a pain though: US9580373B2 - Extraction and purification of urushiol from botanical sources.