Say I am a Cleric, and I want a scroll of Cure Light Wounds. I have a friend, a Wizard, with Scribe Scroll. Can I supply the spell while he scribes the scroll? Or is he only allowed to make scrolls he can use? How would you rule this, and what is the RAW for it?
This gets more interesting when the spell occurs on more than one list but at different levels. For example, Dimension Door is Summoner 3rd and Wizard 4th. Can the Wizard make a 3rd level Dimension Door scroll if a Summoner supplies it?
/cevah
PS: Yes, I could UMD it, but I don't count that for the sake of this question.
Cooperative Crafting seems to be closest to what you want, though both people need the item creation feat.
Otherwise, I would say no.
The creator must have prepared the spell to be scribed (or must know the spell, in the case of a sorcerer or bard) and must provide any material component or focus the spell requires.
[edit]Hmmm...Looks like I didn't read enough.
If you need another character to supply one of an item's requirements (such as if you're a wizard creating an item with a divine spell), both you and the other character must be present for the entire duration of the crafting process. If the GM is using the downtime system, both you and the other character must use downtime at the same time for this purpose. Only you make the skill check to complete the item — or, if there is a chance of creating a cursed item, the GM makes the check in secret.
If the second character is providing a spell effect, that character's spell is expended for the day, just as if you were using one of your own spells for a requirement. If the second character is a hired NPC, you must pay for the NPC's spellcasting service for each day of the item creation.
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I think the wizard can absolutely scribe the scroll if the cleric provides the casting. You are basically having two characters spend 8 hours to create a single item.
Note that all items have prerequisites in their descriptions. These prerequisites must be met for the item to be created. Most of the time, they take the form of spells that must be known by the item's creator (although access through another magic item or spellcaster is allowed).
The line that Samasboy1 quoted about needing the spell prepared shows up in every item creation process, and seems to be a reiteration of the need to meet the pre-reqs. It looks to me that the feat is intended to allow you to create items faster and give a slight boost to your spellcraft check (not a great feat IMO).
So, yes the wizard can create a scroll that he cannot use without UMD.