The oil filter location on the CX is a classic example of the engineering on this car.  It's either brilliant or completely stupid.  The oil filter is the latter. Whatever engineer let this design out of the factory is a complete fucking tard.
To start things off, here's the oil filter on the Volvo.  It's behind the radiator, under the A/C compressor.  You don't even need to put the car on stands to change the oil.  At least, I didn't.  My first oil change on the Volvo left me thoroughly pissed off at the Citroen's design.
This is the best shot from above of the oil filter on the CX, it's so buried. 
So, since the car's being reworked, I decided this would be a great time to install a remote filter. I had already used a remote filter kit to install a filter for the LHM, so I was familiar with the design.
I got  it from  .  Here's Summit's photo of the kit:
This job is a lot easier to do now, because many of the components  that block access to the filter are not there.  The air conditioner ducts are out, so I can reach around the crossmember, the radiator is out, so I can rotate the motor forward for better access,  the right driveshaft is out, so I could reach up from underneath the car (I did not need to). 
After setting out the tools and parts, I rotated the powertrain forward to allow access from the top.
I used a ratcheting tie-down to hold the motor.  One hook on the mount for the windshield wiper, one on the motor.
Remove the pin on the porkchop mount
And loosen the tie-down ratchet to allow the motor to rotate forward, allowing more room around the oil filter mount.  The motor is heavy, so be careful when allowing the tie-down webbing to loosen.
In the centre of this image, you can see the oil filter mount - it's a cast aluminum piece that bolts to the engine block.
The oil filter mount comes out.  14mm head on the bolt.
After I removed the oil filter mount, I pulled the motor back up to its normal position and put the pin back in the porkchop mount.  No reason to have the motor mounts and the tie-down strap under constant strain.