The motherboard must be removed to install the retention module, which may take some time. Once the module has been mounted on Socket 478 with four screws, or on Socket 754 with two, the cooler is fixed with two retaining clamps. This should be done while the board is removed. Assembly is much more difficult if it's still in place.
If the user opts to use the fan supplied, it should only be screwed on after installing the cooler, otherwise it is tricky to get at the retaining clamps. At least the operating instructions draw attention to this.
Mounting the Hyper 6's cooler - with the Intel boxed model a matter of seconds - can take an hour or more depending on the casing.