Well, cleaning that intercooler is really tricky ... actually no, it's a piece of cake! There's only one thing to watch out for and that's the expansion of the petrol as it moves through the intercooler. Let me explain how I do it.
Remove the intercooler and have a large tray/bucket and a few litres of ordinary unleaded petrol handy. We use petrol because it dries fairly quickly, is a wonderful solvent for oil and if a small (tiny) amount remains in the thing and makes its way to the engine it's not going to kill it (it won't go through the fuel pump which is the biggest concern).
Now it's easy. Put one hand over one of the intercooler's openings and have the intercooler sit above (so your hand is at the bottom). Pour a small amount (100ml should be enough) of petrol into the other opening.
Now, place your hand over the upper opening and turn the intercooler upside down, releasing the hand that is now at the top (you'll feel it pressurising anyway). Repeat this a few times, then pour the petrol into the container. It should come out quite black.
Repeat the previous paragraph until the fuel starts to come out with some colour. At this point you've gotten the majority of the oil out, there will be a small amount still in there but it shouldn't trouble the car at all. Sit the intercooler down for about an hour or so (in the sunshine helps).
Reinstall and enjoy.
As for the catch can ... almost all of them will do a reasonable job. Putting some stainless steel mesh (like those dishwashing scourers) in the bottom will help it grab the oil (oil will condense on a surface more readily).
