The hill doesn't have to be big by any means. In reality, what you could do is dig a 2 foot by 2 foot (or bigger if you want) hole, fill that hole with manure and compost, , and then mound up the manure and compost mix about 6 inches higher than the surrounding soil, and plant the seeds about an inch deep there.

Alternately, you could start the seeds in pots indoors, then transplant them to the hill after they get a true leaf or two. This would allow you to start them earlier.

You may have misunderstood...many gardeners will hill up small mounds to plant their pumpkin seeds in. We hill all our pumpkins and squash plants..the hill stands up higher and seems to get warmer in sun and seeds germinate quicker and also it's easier to spot bug or spot squash borer attacks.
Also planting you seeds in hills keeps them from washing out in heavy rains.We learned first hand a couple years ago when we got heavy rains for 3 days straight. Areas of our garden were washed out but the little pumpkin plants were standing high atop their little hills unaffected.We plant over 1000 hills of pumpkins and only lost about 30 to water run off.

Waterlily, where do you live and garden? A lot depends on one's climate. For instance, Sueloring is in zone 4 and finds that it really helps to mound up soil and plant on the mounds. I assume her climate is pretty cool, with a shorter growing season. I, however, live in Oklahoma with a long hot growing season. I sometimes grow my squash and pumpkins in "hills" meaning I simply group two to three seeds to one spot. But I don't make a mound. In fact, I often plant in a depression, so I can more easily water during the hot season. In the strictest sense "hill," in squash and pumpkin planting terminology really only means a group planting. The other option is to plant in a row. When I want a lot more of a given squash I will pour a line of good compost where I want my row and turn it under with a fork. Then I plant my squash in that row of enriched soil, perhaps a foot a part.

Another matter of terminology is that of the names "squash" and "pumpkin." Most people think of pumpkins as being round and orange, or at least round; and squash being most anything else. Strictly speaking any pumpkin is also a squash. So, if someone mentions "growing squash," you can know that what follows will also apply to your pumpkins.

Happy gardening!

George
Tahlequah, OK