What you are asking is something which is not supported by Oracle. They update their middleware from time to time, things like the BPMBroker, and you may not be able to tell what is wrong if you choose to hack your system in this fashion. You also run the risk that someone may install a full package from the deployment server which could potentially cause you grief.
That being said, all you really need to do is extract the system.cab (and system2.cab files in the latest Tools Releases) from the executable you download from JDE. Then you can extract the individual directories and files into a temporary location, call it anything you want. Remember you need to use 'system' when you actually apply it to a machine. Once you've got this, make sure you cover any other Tools Release specific dependencies such as copying the .Net runtime libraries into your %windir%\system32 directory.
It is always best to do this on a machine where you've already installed a fat client from the deployment server. It doesn't matter which version of the Tools Release you have running. This will make sure you have the appropriate registry keys applied to the machine. Alternatively you could export them from another machine and import them into the registry. I would only try this in a development architecture, never anyones production system. Shame on you if you do and you have problems.
It is a quick and dirty way to verify a new Tools Release on a workstation and a lab Enterprise server without needing to backup your deployment server and risk taking it down for a few hours if you hose up the install, or worse, you apply it to DEV and cause problems for some critical project which has managements attention.
