Putting the proper seals/grease on there is a good idea. You need to place it as close to the main drop as possible. There should be plenty of room to put one in there, they are not that big of a filter. -- Ex-Tech at the Beach. I speak for myself, not my former employer.
I bought a slightly different one than the one I already had. This one is advertised as being waterproof and is a little stubby and round. The other one was narrow and longer. I'll also use the rubber gasket-type things that fit on the connector.
So I put the filter on outside where the cable line comes into the house. I can't really tell any difference, but hopefully any baddies that were escaping over the last 2-3 years will now be contained.