If you're talking about "pounding on the heads" to get them on - don't ever do that! Why - because you migth get them on ONCE, and you may never get them back off. You'll either need to bend/align the studs (if they are stock and softer type originals) or you may need to make the holes in the heads a bit larger (not a big deal) - or a bit of both.
If you are talking about pounding on the sides of the studs to 'bend them' so they align better (using the method FlatJack9 mentions) - I have done that with STOCK Ford studs (as they are not that tough of material and are probably 'Grade 5' or so). If you're talking about a set of aftermarket studs like ARPs - then I would not suggest this method as they are a very high quality and you might just hurt the block.
I always use new ARP Studs as they have a nice Allen head socket on the top. I only put TWO studs in the block to start - and get my gaskets on and place the head on. Then I put each stud in with a socket wrench and an Allen socket - with good sealer on the coarse threads. This way, I'm not attempting to get 24 studs to go into 24 holes - just to get the heads on.
Removal: I take one stud OUT at a time (with an Allen socket) - and then easily pull the heads later on. Trust me - this is the way to go with aluminum heads and studs!
