My gaming group is finishing the Final Sanction adventure and I am already thinking up new adventures and i was thinking what if i took an adventure from the Ciaphas Cain Series of books? Specifically the Caves of Ice book, so anyways how well do you all think this would work and play? and what do you think about the idea in general?

Haven't read that book specifically, but in general I steal from books, movies, etc. (other forum posters!) with great regularity. The trick to making it work -for me - is to remember some key points when I make the adventures:

1. Most books and movies have 1-2 key characters, but your gaming group is going to be filled with more than that- remember to account for that when you're 'converting'
2. Media can contain a lot of contrived circumstances and contrived revealing of information that can either be missed by players or feel really artificial (watch an episode of one of the 101 Law and Orders and you'll see what I mean by contrived information being revealed). For some reason things tolerated on paper or in a movie seem really awkward in an RPG (one reason is that it usually involves NPCs doing the telling)
3. Let the players decide how the plot turns out, don't try to railroad them into following the plot of the book (deus ex machina is more tempting when converting from somene else's work I feel, then when inventing your own)

Caphias Cain isnt bad inspiraton, but it fits dark heresy a little better. That being said, i have actually used a situation pretty similar to the book 'for the emperor', which has both tau and tyranid and heavy fighting alone in underground environs, as well as mystery and inquisitorial involvement. You could probably use caves of ice, but necrons arent very throughly statted out in the rpg books. Another potential concern is just how weak and small a kill team is against an entire tomb, and if they feel compelled to cleanse t without thinking of filling it with promethium and just blowing it all up things could get ugly.

I could have them take a different route than the one Cain took through the tomb then they may not be tempted to cleanse it themselves

Is that the one during the Ork invasion where they find Necron tombs? if so, awesome- as I was reading it, i thought 'this would make a good DW adventure'.

yeah its that one I was thinking another good one would be the one where they diffuse a situation with the tau and fond a hidden tyranid infection