Humans already are able to have ears halfway there.
In most people, protruding or prominent ears are caused by an
underdeveloped antihelical fold. When the antihelical fold does not
form correctly, it makes the helix (the outer rim of the ear) stick
Ears that look like this work just fine. The only reason to "fix" it is aesthetic (children are often teased). Even the doctors refer to it as "bat ear" or "Dumbo ears" on their websites.
If you want an even less developed antihelical fold, it would be well within the limits of human evolution to achieve. Just select for it. Any reason that gives people with this type of ear more of a reason to reproduce will work. It can be direct (person is more likely to have sex) or indirect (people with protruding ears get all the best jobs and are therefore more likely to find mates...may or may not work in any given culture but...).
Elongating the helix is a more difficult change. But there is a genetic condition called Stahl’s ear (aka Spock's ear) that does this, pointy top and all.
Stahl’s ear is the result of misshapen cartilage. It is characterized
by an extra horizontal fold of cartilage (crus). Normally, there are
two: superior and inferior. In Stahl’s ear, there is a third
horizontal crus. The helix (or upper portion of the ear) may unfurl,
giving it a pointed shape. This gives the characteristic “Spock”
appearance to the ear. (ref)
Again, there is no different in the ability to hear or anything else. It's all about looks. And looks matter. The ears you want can happen with just two changes to the standard ear. Select for these and you're golden.
But why would these be selected for? Other than considering them sexy (the sort of thing that usually changes in a few generations, if not sooner), what justification could there be for picking one type of ear over another?
And the answer may be, there's not much. Because these types of ears don't cause harm (or benefit) or change hearing, which type moves forward as the standard ear is more about the luck of the genetic draw when a group of humans is small and isolated then grows quickly.
Imagine an extended family (a few hundred people), where both these genetic variations are common, migrating to a new land. Then the people on the old land are mostly wiped out. The species continues to grow from the migrant group, incorporating a few survivors from other groups.
Add some sexual selection into the mix and whoa! elf ears!