Since you'll be here on the Disneyland trip I'll assume you won't be showing a car. (Correct me if that's wrong.)
That means you won't have to worry about getting there early enough to get a spot. The display area fills early, spectator parking doesn't fill up. As long as you're there before 08:00 you should be OK.
Further assuming you'll be staying close to Disneyland, you'll <span style="font-weight: bold">head south on the 5 freeway</span>, about 14 miles, to the Alton exit.
<span style="font-weight: bold">Exit at Alton</span>.
As you approach Alton (just after passing the 133 interchange) you'll see the location on your right. The building along the freeway has the Taco Bell logo on it (used to have FORD) and the Mazda building is set back a little from the freeway.
You'll pass under the Alton bridge, the offramp is on the right. The offramp hooks you in a tight 180 degree right-hander (onto Enterprise), taking you up to Alton.
<span style="font-weight: bold">Turn left onto Alton</span>, swinging wide to the far right lane of Alton because you'll be making an immediate right.
<span style="font-weight: bold">
Turn right onto Gateway</span>.
Spectator parking is the <span style="font-weight: bold">first driveway on your right</span>.
Everybody has their own habit at this point. Some people park in the front of the lot and walk in across the front of the building. Some people park in the parking structure. I like to park in the back, up against the freeway and walk in around the back of the building. For the first timer it's probably most interesting to walk in front.
Here's a
Google map.
Here's the old flyer (again, the building says Taco Bell these days, not FORD).