Hi Loek,
I recommend reviewing my colleague, Jason Straub's blog on this topic: Application Express Nuggets: Oracle Database 12c Multitenant Option and Application Express, where Jason explains that our latest patch release, APEX 4.2.2, does not contain the patch installation files for a 12c container database, because 4.2.2 was released prior to 12c:
...we have not released a new version of Application Express since Oracle Database 12c was released two days ago, so there is no software available to upgrade or patch the version of Application Express (4.2) that comes in the container database. The next version or patch of Application Express will contain the appropriate scripts to update a container database...
So until the next APEX release is made available, you would need to stick with the version that comes with 12c, which is currently APEX 4.2. I hope this helps to clarify things.
Regards,
Hilary
That would make sense, I guess that's what happens if you try to be bleeding egde 
It was not all a waste of time, I did learn alot about the new multitenant architecture in the process.
Hi Loek,
I just wanted to inform you that we now have a revised APEX 4.2.2 OTN distribution available, which contains the necessary scripts to install APEX 4.2.2 in a container database. Jason has blogged about this new distribution, here, and has also outlined the necessary steps to follow in order to install 4.2.2 in a container database. Please note that this does not cover the patching of a container database from 4.2.0 to 4.2.2, but instead covers the removal of 4.2.0 from the container database, and then the fresh install of 4.2.2 in the container database. Hopefully this will help you to get the result you were hoping for - to have 4.2.2 running on your 12c database.
As mentioned in my previous post, if you wish to patch 4.2 in your container database to 4.2.2, you'll have to wait til our next release, as it will contain the necessary patch scripts for that upgrade effort.
Regards,
Hilary
Loek,
There is also now a brand new page on the Application Express OTN page all about APEX + 12c. Click the Collateral button and then the Application Express in Oracle Database 12c link.
Regards,
Jason
