KMatch

I'm not sure I follow here about the difficulty part. It simply needs 12v. You can tie into an ignition circuit which will have the choke heating the whole time the key is on, sometimes causing a cold start problem if the key is on a bit before startup, or you can use a controlled circuit which uses an oil pressure switch (used with a light) to control a relay which only allows the choke to heat up when the engine is actually running. The best and easiest is to just piggyback off a distributor hot wire in most cases. Use scotch locks if you like spending time on the side of the road in the rain trying to figure out why it won't run, or a good heat shrink butt connector works fine when properly used. Solder is best, but overrated as this will likely be the only soldered connection on the whole car.

kalli

not a bother. most people connect the choke straight to the wire coming from your ignition switch to the distributor. my guess is that the HEI ones still have those.
has the disadvantage that it'll run with ignition on, but usually that's something noone does anyway.
So what holley recommend (same as edl as far as I know) is to just hook it up to the STA terminal at alternator. This way choke will engage whenever the engine is running (the preferred way).
in any case, that's the simplest thing to work around