A spell prerequisite may be provided by a character who has prepared the spell (or who knows the spell, in the case of a sorcerer or bard), or through the use of a spell completion or spell trigger magic item or a spell-like ability that produces the desired spell effect.
If I have a Wizard with Scribe Scroll who is able to cast a spell not on the Wizard's spell list as a Spell-like Ability, would he be able to scribe a scroll of that spell?