Well, let's think of this for a moment...
First, let's assume the player cares about his character's alignment. If he doesn't care, there's no chalenge, and not much fun.
If he cares, then if he's handed a book that's mostly necromancy and summonings, and he can see that most of them have the [Evil] descriptor, he'll simply not use them.
But, here's a few things to consider...
How does he know they have the [Evil] descriptor? Is that knowledge automatic with a spellcraft check? There are lots of necromancy and sumonings that don't have that descriptor, so their school is not enough information.
Summonings are tricky - Knowledge (arcana) may very well tell you if the thing you manage to summon is in fact a demon. At least, it will if it's a
common demon. If it's a highly rare form of demon, and doesn't
look demonic, the PCs may not catch on....
So, what you do is not tell the player there's an [evil] descriptor on the spells. Make it only one summoning spell. Make it summon something that doesn't look demonic, or act flagrantly evil immediately. Make the spell reasonably powerful for it's level, so the player is tempted to cast it repeatedly. Unless someone actually thinks to Detect Evil on the summoned critters, you can start leading the wizard down the well-intentioned-paved road.
As for advice from a demon, and whether the players are willing to take it - that's why you make the demon chatty. The demon talks about things innoccuously for quite a while. Get them used to talking with it such that there are no repercussions. Then, you start slipping minor things as part of the chatter. Once they start taking those, you can move onto bigger things. Chatting turns into discusssion, turns into planning sessions.
This is a really long-term project. It works much better if the players don't know the thing's a demon to begin with, too.
Of course, using the demon to frame the PC for murder is also a coolness
That'll teach him for calling on demonic powers. If he survives it, he'll be wary of demons for a long, long time...
Which is why the demon in question knows a succubus with the appropriate magics to mask her alignment. You see, that demon is only a scout. He reports back that there's this guy who's ripe for the picking, and where to find him.
Heck, try this setup - the current demon is a shill. His job is to make the wizard hate demons with a passion. The demon puts him through hell. The succubus then, is there to use that hatred -
slowly lure the wizard to doing evil acts in teh name of destroying demons. After all, the legions of the Abyss are many - they can sacrifice a few to earn souls...