Just now I've had what seemed to be a very stupid thought: getting the Ultimate Good ending as Evil Alcedor (not Swordcedor, Evil Alcedor specifically). Considering the trigger for becoming "evil" is just completing the First Summoning, all you need to do is do that quest then finish the game.

Of course it doesn't sound simple; people already have trouble getting Redemption done as is, but I crunched the numbers, and provided the "Greater than" on the morality score page quest requirements actually means "Greater than or equal to", it should be JUST possible to do it, as long as you got the Necronomicon before finishing First Summoning.

So that's all. I'm editing Paimon Returns as we speak, and once I'm done I'll try to get the quest given to me with just -13 score to figure out this question once and for all, but if I get a 100% certain answer beforehand I'll be happy too. The best part is that this shouldn't require cheats, just a lot of weird ass routing.

EDIT: Nevermind, I spoke too soon. My method of getting to the morality score needed to get the quest in the first place involves burning all towns, and that would make getting good morality score out of Master Arsonist impossible. Still I'd like to know if anyone else has any ideas.

EDIT 2: Unfortunately it seems the max moral score you can get if you want to pick up First Summoning is 33 (it took me a surprisingly long time to remember that the guy at the start of the game also affects the score), which is ALMOST enough to get the Protect the Relic quest, but even then you wouldn't be able to get enough moral for Gather Reinforcements with the reward from that quest alone.

The only way this would be possible (and yes I checked the metadata sheet and the values are for greater than or equal to values) is if helping the guy at the start of the game didn't give you moral AND you could get the good morality score out of Flood Arkos even after going ahead and destroying the dam by yourself, and even then you'd still be missing -2 morality score to actually be able to accept this.

Although it ended up surprisingly closer than I thought it would ever be, I'd say Ultimate Good as Evil Alcedor is not doable without the use of external tools, at least until either we find out about a glitch that lets you mess around with your score outside of quests and stuff or new quests are added/changed.