Well this has annoyed me for ages, so I finally hammered it out.

Background - the Identify Spell from TL1 does not work in TL2. As a point of interest, since the whole UI mechanism has changed between games you can't make it work either since the IDENTIFY effect now seems partly hardcoded - the game is now hardwired to check for and utilise the unit type IDENTIFY_SCROLL only. Dammit.

So what I have done here is the next best thing I guess, and it works as close as dammit to the original. It's just a very clever workaround that creates a spell that resides permanently in your spells inventory (it does not need to be learned). As long as you have this spell in your inventory, you can use it just like an Identify Scroll except it lasts forever. Other than that it operates and works just like any other spell but has the advantages of not taking up a spell slot and making Identify Scrolls into vendor fodder.

If you want to test it out, you can download the mod below but note that I haven't configured it to drop at all, this is just proof of concept. You will have to console the item with the 'ITEM IDENTIFY SPELL' command.

https://drive.google.com/file/d/0B5w_m-h6MlfvZHdrU01HQkhJQ0E/view?usp=sharing

This features in the next version of Unearthed Arcana.

Now if somebody can just make it consume mana when used it would be perfect

Is the identify spell item something that actually gets used like a consumable?  If so, I suspect you could just add an effect to it in the Effects list, something like Mana Recharge and give it a negative value, instant duration and voila.  I'd probably set the min/max to the exact value I wanted and set NoGraph to true.