Yes!! Even adoptive mothers have been able to breastfeed, and they didn't have all those hormones helping to get it started! (There's a good section on kellymom about re-lactation, although the section on low supply might be better.)
http://www.kellymom.com/bf/supply/index.html
http://www.kellymom.com/bf/adopt/index.html
The kellymom website is a WONDERFUL resource for breastfeeding and other attachment parenting issues.
If your babe is trying to nurse, she will be able to do a much better job than any pump. (at least in terms of sending the message to your body that milk is in demand and your body needs to step up production.)
When my first was 4 months old, I got a nasty cold and my whole body was dehydrated - I saw a lactation consultant who said "Wear that baby like a bra. If your family wants to help you, don't let them watch the baby while you rest. They can wash dishes or make you meals or do a ton of other things. You take that baby to bed with you, lie down together, and just try to get him to nurse as often as you can."
She also recommended rich, nourishing foods for me (oatmeal, nuts, avocados - those are high in healthy fats, and breastmilk is rich in fat.) And I always took a fish oil supplement (also known as DHA supplement) because those have the healthiest fats (omega 3s) and they pass into the breastmilk and are great for building baby brains.
I've heard sometimes that TOO much water can be a problem, so don't force yourself to drink, drink, drink way beyond your thirst. I also tried the fenugreek and mother's milk teas, but I'm not sure it made too much of a difference.
The MAIN THING is that your body will respond to the baby's demands. Any time that kid opens her mouth, try to shove a nipple in it - "wear her like a bra" - and you should see the supply kick in.