Hanley is right about the lockout strength issue. Think of a denim bench as a something like a 3 or 4 board press. Therefore, your mid-range and lockout strength will be critical to your carryover. My recommnedation is to get a pretty tight one- it should be pretty damn hard or impossible to touch at first. Then, train in it every week for a while.
Hit 2,3,4 board for reps- like 3-5.
Then take some a few full range singles- not maxes- but heavy weights. Wet the shirt every workout- I mean soak it. That will make it easier to touch and will make it springier.
Again- if you can touch the first workout with mid-300s or less- I suggest sending it back and getting an inch or two taken out of the chest (very common on Inzer shirts) and maybe getting the arms pinched as well. One other word of advice on ordering- get a 2 inch scoop on the neck and order the radical cut. Good luck.