I had a very long labour (50 hours) without pain relief, because I never really felt I needed it. Early on walking around and being upright was all that was needed, later on concentrating on each contraction and having DH press really hard on either side of the base of my spine during contractions made most of the pain go away on its own. I was at home, though, so felt more confident and in control than I would have in hospital. I found that thinking of each contraction as having a beginning, a middle and an end was helpful - they were predictable, I knew what was happening, I knew what my body was doing, and that all made it easier to cope with.
Ended up in hospital after DS got briefly distressed during the second stage, ventouse delivery, still without pain relief but I really didn't need it by then, I didn't find the second stage painful at all, just tiring. The only really excruciating bits of the whole experience were the vaginal exams and the stitches afterwards; for those I'd have taken an epidural gladly if there was such a thing as one that only lasted five minutes. (I did have a local anaesthetic for the stitches, but I'm not convinced it worked because I felt every one of them.)
I don't think you can guarantee that any of these techniques will help, though - a lot depends on the position of the baby, your particular way of responding to pain, whether there are any problems, a ton of things. I'm expecting DS2 any day now, and I'm just trying to keep an open mind - I know it's possible for me to labour without pain relief, but at the same time, if that doesn't work for me this time around then I'll be grateful the medical options are available. My best advice is to make a long list of things that you think might help you cope with labour, write it all down because it will all go out of your head when you're actually in labour, and then try everything on the list until you find something that helps, and if nothing helps then go for the medical options because that's what they're for.