After taking a quick look at the Gnomes through D&D’s history and even going so far as to provide yet another variant for them (actually two if count this one), I remember that I also promised a replacement. Well, here it is.
For reasons that I can’t fathom (besides lack of famous and contemporary literary sources), Gnomes were never famous with most D&D players. While writing a 1st Age-style setting for a stillborn D&D 4th campaign I decided to remove Gnomes and use instead Satyrs. Like the former, Satyrs are well-known visually but have the bonus of being a "cool" race for most players (it’s easier to describe a badass or impressive Satyr than a Gnome). Also, unlike Gnomes, Satyrs (or Fauns) are usually taken more seriously by most players. A third element in favor of our woodland cheering/dangerous dwellers (depending on which myth you take them) is that Gnomes were definitely getting more Fey-like with each version of the game (both Pathfinder and D&D). Finally, legends regarding Satyrs are easy to implement (for example, here and here).
I’ll provide just my stats for Satyrs in Pathfinder. They’re complete unrelated to the monster stats in the Bestiary I (or the Faun at Bestiary III). As I said, Satyrs are so well-known that I leave background-related information to each Gamemaster. Some will use them as sylvan bards (where, ironically, they’re indeed a better choice than the D&D 3.5 Gnomes), other as dangerous feyborn creatures (in this case, a good replacement for the Pathfinder/D&D 4th D&D).
Satyrs for (almost) all Types of Ye Fantasy Game:
+2 Dexterity, +2 Charisma, –2 Intelligence: Satyrs are crude but agile, and their attitude makes them naturally agreeable. [If going for a more “dark fey/devilspawn” version, I recommend +2 Constitution, +2 Dexterity, –2 Intelligence]
Hopping Hooves: Satyrs are natural runners and have a base speed of 40 feet.
Satyr Magic: Satyrs add +1 to the DC of any saving throws against enchantment spells that they cast. Satyrs with a Charisma of 11 or higher also gain the following spell-like abilities: 1/day—dancing lights, ghost sound, prestidigitation, and speak with animals. The caster level for these effects is equal to the satyr's level. The DC for these spells is equal to 10 + the spell's level + the satyr's Charisma modifier.
Hatred: Satyrs receive a +1 bonus on attack rolls against humanoid creatures of the orc and goblinoid subtypes due to special training against these hated foes.
Carousing: Satyrs get a +2 racial saving throw bonus against poisons and intoxication effects. They receive Endurance as a racial bonus feat. [If you must, give Satyrs a +2 racial bonus with Performance; also, a few racial feats can easily simulate their famous “pipe magic”, maybe stealing the ability shown on the Faun description.]
Forestbound: Satyrs receive a +2 racial bonus on Stealth and Survival while on forest terrains.
Fey-touched: Satyrs are also considered of the Fey subtype for the purpose of effects that target Fey. Satyrs receive a +2 racial bonus on Diplomacy with intelligent Fey creatures.
Weapon Familiarity: Satyrs are proficient with longbows (including composite longbows) and shortbows (including composite shortbows).
Languages: Satyrs begin play speaking Common and Sylvan. Satyrs with high Intelligence scores can choose from the following: Draconic, Dwarven, Elven, Goblin, and Orc.
For your “instantaneous Satyr” pick the Elf race entry, from the Player’s Handbook I, remove Group Awareness and replace it with the Iron Stomach trait (from the Dwarf race). There’re myths where Satyrs are famous gluttons. The Elf mechanics are already perfect for them.
Swords & Wizardry White Box
The easiest way for me is to use either the Elf Variant class or the Halfling class.
The “Elf Variant option” represents the magical Satyr – good at magic and at battle. I recommend ruling that the Satyr needs his magic pipe to cast and that all his spells are music-based.
The “Halfling option” represents the sylvan-type Satyr – good at hiding and deadly with bows. I recommend removing the Hard to Hit and limiting his Deadly Accuracy to bows. Finally, change his Saving Throw bonus from “magic” to “poisons and charms”.