Well, it worked, but it was a bit of a pain.
Starting about 1-2 weeks after subscribing, call (888) 267-3684 and ask for your ESN number. If they give you only 9 digits, add a 0 in front of it.
Then go here:
http://insider.espn.go.com/insider/espn-the-magazine/
Enter the ESN number in the box near the right-bottom where it says to get free insider.
It will ask you to re-enter the ESN number and then a bunch of your info.
It will then ask for a credit card but not charge you anything. I got stuck on this part because it wouldn't accept the prepaid card I used (not sure why). However I called them at (888) 549-3776 and they were able to manually force it through.
So I have ESPN insider for $8.25 for a year, plus the magazine.