This ruling predates the Dungeons and Dragons 3.5 revision, but as the topic's remained unmentioned since then (so far as I could determine, anyway), this ruling should be applicable to any 3.5 campaign with minor revisions by the DM (DMG (2003) 4). Although then-Sage Skip Williams's Rules of the GameRules of the Game columns should be read with salt shaker in hand, he's still one of the three primary designers of Dungeons and Dragons, Third Edition, giving this ruling at least some credibility. (By the way, at the time, Dragon was still published by Wizards of the Coast, not Paizo, if that makes a difference in determining if something's authoritative enough for your group.)
A wizard that acquires an arcane scrollscroll of cure light woundscure light wounds [conj] (PH 215-6) (1st-level spell at caster level 2) (DMG 239) (50 gp; 0 lbs.) or even a divine scrollscroll of cure light woundscure light wounds [conj] (PH 216-7) (1st-level spell at caster level 1) (DMG 241) (25 gp; 0 lbs.) must follow these steps to get it into his spellbook:
- The wizard must decipher the magical writing on the scroll of cure light wounds by either making a Spellcraft skill check (DC 21) or employing the 0-level Sor/Wiz spell read magicread magic [div] (PH 269).
- The wizard must understand the spell cure light wounds by taking 1 day and making a Spellcraft skill check (DC 16). Note: Some restrictions apply.
- The wizard must copy the spell cure light wounds into his spellbook by taking 1 day, spending 100 gp, and having the spell occupy 1 page of his spellbook.
The Player's Handbook on Spell Preparation TimeSpell Preparation Time says, "After resting, a wizard must study her spellbook to prepare any spells that day" (178). That is, if a spell's in the wizard's personal spellbook, the spell's already gone through the process above (or a similar process that's led to the spell being in the wizard's spellbook). Nothing prevents the preparation of any spell in the wizard's spellbook—even if the spell's source is weird or its typical list alien.
The wizardwizard class feature spells says, "A wizard casts arcane spells... which are drawn from the sorcerer/wizard spell list" (PH 56). While the text doesn't say a wizard can't cast spells from lists other than the sorcerer/wizard spell list, the game usually uses inclusive language (explaining what can be done), saving for confusing corner cases exclusive language (explaining what can't be done). That is, just because the text doesn't say the wizard can't doesn't mean the wizard can, for example, turn his foes into lawn furniture (at least until the wizard can cast polymorph any objectpolymorph any object, anyway).