the hasport guy is a fucking retard if he told you that, and frankly, i don't buy it. I've spoken with Brian several times.. maybe you got an intern?
here's the deal.
CX ecu is NOT wired/plugged/has control over for vtec. never has. never will be.
without the p28 (ecu from the d16z6), there is no way to control VTEC Correctly. there are hacks- such as the RPM activated switch with an ignition pill, or a manual switch that you push- but frankly, both those options suck balls, will not give you the best power, and in the long run, will hurt your motor. timing maps are different under vtec, so are fuel maps. no vtec switch can adjust for those.
your cx distributor will work fine.
you need the z6 intake manifold if you want a power gain, as the cx uses shit that's way to small and won't flow for the life of you. but i don't see why the CX IM wouldn't work.
as for the harness, frankly, its the easiest way to go. Yes, you don't need it... but there are several plugs on the z6 that the cx does not have. Now, how do you intend to plug in to a harness without the female (or opposing should i say?) end of the connector to go into it? you are only going to find that on the z6's harness.
Yes, you could hack some wire clips onto it which will probably fall off.
it's your car, and your choice- but the harness is the way to do it.
now, after the z6 harness is plugged in, that gives you the proper wires run to the shock tower mounting connections on the passenger side. from there, you will need to run the wires down into the ecu on the passenger side kick panel.
after all that, you will need to convert to a 4-wire o2 sensor, as the CX has a 1 or 2 wired depending on the year. Again, this will take you up to the shock tower plug, and the other wires will need to be run, as they are not part of the cx chassis harness.
that should cover the wiring.
the oil thing E_Sol describes above must be removed.
the headgasket and belt and pump shoudl be replaced as Massey suggested.
the CX header is a piece of shit. again, if you want to make power, this is not the item to keep. score a z6 exhaust manifold and cat combo if you can't afford an aftermarket one just yet. $25 or so should score you that.
there's a lot more to it that it sounds or what the internet has made it out to be of "slapping on a vtec head". its much more involved. torquing the headstuds correctly, getting the timing right with the timing gun... the list can go on.......