You could do that in a previous edition - 1st or 2nd, I think - but you can't in 3.5. Why? Well, under 3.5 mechanics, if you could treat a spellbook as a scroll, almost no wizard would ever actually make a scroll over maybe a 4th level spell. Why? Well, scribing into a mundane spellbook costs 100 gp per page, and a blank spellbook costs 15 gold pices. So a 9th level spell would cost 915 gp to make for casting out of the spellbook. A caster level 5, spell level 3 scroll has a market value of 375 gp. That's 187.5 gp and 15 xp to scribe, while writing it into an otherwise blank spelbook would be 315 gp, no XP (includes cost of spellbook). A caster level 7, spell level 4 scroll has a market value of 700 gp, that's 28 xp and 350 gp to scribe. Writing it into an otherwise blanke spellbook would be 415 gp, no XP (includes cost of spellbook). Is 65 gold worth more, or less, than 28 xp? A caster level 9, 5th level spell scroll is valued at 1,125 market; 562.5 gp and 45 xp to craft. A 5th level spell in an otherwise blank spellbook costs 515 gp to make.