I had the same problem. The only way to get the hosing in is to drill 2 holes into the top of the tank. I used a 1.5" hole saw and carefully drilled it. I tried to follow every tip I could find from this forum on how to drill a tank. It was pretty scary, but eventually I got it done.
The good thing about using 1.5" holes is that the hoses fit in almost perfectly but leave a little extra room in case you need to run an airline or something through the same hole. Plus, you don't need to use those snap on clamps that come with the FX5. The hoses pretty much stay in place just by putting them through the right size hole.