NCAA Football 08

I got this from Augustus' guide on x360a. I can vouch for it 100%
Note: I don't know what play he's talking about, but I used Cross Up from page 8 of the standard pass playbook and it worked fine.

"Recommended Scenario: 15 Minute Quarters, Heisman Difficulty, all sliders at 100 for user, two controllers, Idaho vs. USC

How to Achieve: Play against yourself, with the account you want the achievement in as USC. With the Idaho controller, go to standard pass and on the 8th (maybe 7th) page there will be a play in the bottom left hand corner that has the Idaho WR running a straight route alone. In USC, go to 4-3, then the first play in the upper left hand corner. Substitute the first Idaho receiver on the depth chart with one of the lower players, ideally a quarterback or the slowest person available. Immediately snap the ball with Idaho and tap B. The QB should lob it right to the USC corner, who will catch it 80% of the time (which is why we put it on Heisman). Don't do anything fancy with returns, as you can be injured. When calling offense with USC, just punt and repeat the play with Idaho until you have the required six interceptions with your cornerback."

Teams USC vs Idaho
Difficulty Heisman
Time 5 min quarters

Make sure you have control of USC and kick off to Idaho.

What you want to run is under Standard Passes on page 7
Cross Up play -
X man runs a straight route
B man runs a half slant

With USC use 4-3 defense using the Engage Eight play.
Hike the ball give it a second and launch it at the B man. CB 28 should easily pick it off without interference.

I ran it in for a TD each time.

The achievement came after the 5th one for me, but it should have been the 6th.

I tried doing this using 15 min quarters like the other guide but the achievement didn't pop so I tried this and it worked.

Credit goes to "suspect667" here on TA. He posted this solution for NCAA 2009, and it helped me obtain the achievement here too. It's quite simple

1. go to: My NCAA, My Settings, House Rules, Custom AI.
2. Switch computer offense settings QB accuracy to 0.
3. Switch User defense settings: Awareness=100, Knockdowns=0, Interceptions=100, and Break Block=0 (allows cpu more time to make a bad throw)
4. Put difficulty level to Freshman and 15 minute qtrs.
5. Play against Hawaii and on defense use bump-and-run, man coverage all day long and you'll get about 30 team interceptions before you finally have one guy rack up 6 total interceptions.
6. When you get the ball back, just punt the ball away on 1st down.