The set had a detachable cage assy that it was mounted in. In ASSU use it was only held down by a bar across the top, much like a battery hold down clamp.
Thanks to VMARS many of the manuals for the set are available online.
Go to:
http://www.vmarsmanuals.co.uk/archive/files_index.htm
Document 56 gives a lot of info about mounting in 5cwt.
The EMERS are there as well.