What HDD cooler? I like the ones that just sit on the HDD in the 3.5" bay...
It just sits in the 3.5" bay on the drive
In most Antec cases and some good cases, they have an area in front of the HDD bays where you can place a fan. On my P180, I have on in the front and in the back to pull air across them and then onto the PSU.