"do I need the gnome race in particular to do this, or could I make this work with, say, a halfling?"
In my mind, it's really bizarre that the halflings have stolen the gnomes' schtick in so many places.
Gnomes are the fey. Gnomes are the tricksters. Gnomes are the earth-spirit druids. Gnomes are the lorekeepers, the SECRETKEEPERS. Gnomes are the laughing jester spirits of the world. They're shape-changers, illusion-masters, the uncanny and unknowable, the eternal ciphers.
Halflings are the rural Brittish. Halflings are the sturdy, the determined, the resilient. Halflings are the survivors, the cunning. Halflings are the rats of the world. They dwell in shadow only to leap out and take what they want, you cannot exterminate them, you cannot intimidated them, they are the eternal shadow-dwellers.
Those are both really cool and very distinct archetypes, each very close to their roots (laughing trickster-spirits of shape-changing faerie and tough survivors who dwell unseen at your feet).
But halflings and gnomes, in D&D, both suffer from the horrible consequences of the Dragonlance series. There, both were comic relief, but the kender/halflings became a hero while gnomes/tinkers languished as pure comic relief NPC's.
It is this burden which ultimately helped kill both the halfling's solid role and the gnome's solid role, because it became hopelessly muddied. The halfling wound up getting half of the gnome stuff attributed to it, while loosing a lot of the "halfling" stuff that was its legacy from Tolkein (which has now gone to kobolds and goblins and other such small evil guys).
Instead of re-focusing the halfling and going back go the gnomes' roots, 4e decided to further distort the halfling and to ditch the gnome entirely as a race, using it only as a monster.
Now we have insanely vague and unfocused halflings (mostly only focused because of their exclusive role in the PH), and gnomes who kind of kick ass, but who don't have much left of that trickster spirit of old.
Halflings don't need 3/4ths of the junk that has been tacked onto them. They don't need to be LotR sticks-in-the-mud, but working with the idea of halflings as doughty survivors and "rat-like" (while keeping the idea of ticksters and nature-spirits from waffling too far into elf territory) would keep things fairly rewarding for me.
Until D&D figures out what the heck Halflings are actually supposed to be, they get the banhammer in my games. Gnomes are cool, though.