<font color=navy>To add to Michelle's directions, here's the most direct route:
To get to the 105E fwy:
From LAX airport:
Sepulveda South to 105E (the onramp will be on the right-hand side, right after you go under the runway tunnel)
From the various rental car agencies:
Go south on whatever street you're on till you get to Century Blvd. Go east (away from airport on Century Blvd.). The first big street you get to will be Aviation. Go south (turn right) on Aviation, and get in your left-hand lane. The next big street from there is Imperial Hwy. Turn east (left) on Imperial Hwy, and immediately get on your right-hand lane & get on the 105 fwy east. Note that you can get to Aviation right from some of the rental agencies... all this is from 2-3 miles - pretty close.
105 fwy heading east
Like Michelle said, get in the carpool lane, all the way on the left-hand side. You have to have at least two people in the car to be in this lane. Go all the way to the end of the freeway.
605 fwy heading south
The 105 fwy ends at the 605 fwy. Head south, and stay to your right because the 91 exit will be just a couple of miles away.
91 fwy heading east
From the 605, get on the 91 east, and as soon as you can, edge over to the left-hand lane (#1 lane). Stay in the carpool lane till you get to the 5 fwy south. ... side note: The amusement park you'll see off Beach Blvd on the right side is Knotts Berry Farm - right there is also Medieval Times, Wax Museum, and Wild Bill's dinner show.
5 fwy heading south
From the 91 carpool lane, get on the 5 fwy south, and stay in the carpool lane. There is a carpool exit to Disneyland Drive from the 5 fwy.
Disneyland Drive
If you are going to Disneyland Resort, Disneyland Hotels, Coast Hotel, & I think Marriott (the hotels on Katella), then get off on Disneyland Drive. When you get off the freeway, turn left, and go straight. You'll pass the DL Resort to get to Katella.
Harbor Drive
If you are going to the Howard Johnson, Fairfield Inn, Carousel Inn, and other hotels on Harbor, then you'll need to get out of the carpool lane before you reach Disneyland Drive, and edge over to your right. After Disneyland Drive is Harbor Blvd, and hotels on Harbor Blvd.