You know I try to be as green as possible, but I drew the line at poison ivy (fortunately, I don't tend to get it, but I've had housemates that did).
Here's how I got rid of it. Ortho Brush-B-Gone. I bought a bottle of that and a gallon sprayer when I lived in a townhouse that backed to some deep woods. In the summer, the path through there was completely covered by poison ivy a couple of feet high. I kept thinking about all the kids that wanted to walk through there. I started spraying every spring with the brush-b-gone, and over a couple of years, had the poison ivy beaten back to a good clearance on either side of the path. (and cleared from my fence line to the path completely). That stuff was great, and it didn't take down everything like a Round-up would.