In steps:
Wiring -
Yeah, you kinda knew this would take time, patience, and a little majick. The XFi is carb'd, right? So just use the parts of the CRX harness that you need for each part of the XFi engine.
Realistically, the wiring should technically be one of the easiest jobs, after the motor is installed. In
any engine swap, it's almost universally the best idea to use the harness from the car that you're installing the engine into, adding/subtracting wires where necessary.
Going to a carb'd engine, the only things you'll really need to wire in are the starter, sending units, and ignition distributor, none of which should be too difficult. In all honesty, you could run that engine without even touching the CRX's wiring, and using only a battery cable, a switch, a push button, and a couple lengths of speaker wire.
(This is how the woods truck runs now, actually.)
Short form - Unless you plan on using the connectors, ditch the XFi's harness altogether, and just use the CRX's wiring harness to match up wires you need.
(PS - If the XFi was injected, that whole dealy goes out the window... it's still easiest to use the CRX's harness and install the wires you need, though.)
Radiator -
You can either use the CRX's radiator, and add hard line/elbows as necessary, or you can hack the center hood latch support on the CRX to make it so you can install the Metro's radiator at an angle. To hack the center support, you drill about 1/3 of the way down it, a hole about 3/8", then install a strap from left to right that intersects that hole. Bolt the strap to the support, then bolt the ends of the strap to your core support edges, below the headlights. This should give you enough room to install the radiator at a slight angle, enough to clear the core support and hood.
You may also be able to remove the core support stops (that the radiator sits on) from the core support, and let the radiator sit on the front lower cross member (where the radius rods bolt up).
Using the CRX radiator might also require adapting the hoses for diameter, as well.
Shifter -
This isn't a big deal, although I'm not sure how the linkage works on the XFi. ON the CRX, it's a single pin that hooks the shift linkage rod into the transmission shift rod "nub"... it's commonly called a b!tch pin (sorry, but that's what it's called) because it's a PITA to get in/out. It's just a steel roll pin. In any event, you won't want to attempt to move the shifter inside the car, it's easier to just cut the tube and extend/shorten it as necessary.
If you can get a shifter actuator rod from a Metro 3 cylinder, cut the transmission end off it, and weld it to the CRX's shift lever after the engine is installed, to ensure the proper length.
NYS can take up to 3 months to change a title... their licensing/title laws are VERY different from PA's.