Leveling a floor for laminate installation

We just had our floor measured for a laminate floor installation. In the process of measuring the area, the contractor also documented three crowns in the floor - 2 measuring 1/4" and one at 3/8" over about 2-3 square feet. Home Depot told us they would not do the installation with these imperfections. I've decided to take care of the crowns, and do the installation myself.
Is there a floor leveling compound out there that can be used over vinyl, or will I need to rip this up, and apply the compound to the sub-floor?
I know not every floor is perfect, but are these imperfections big enough to be worried about the subfloor? i.e. - given the size of the crowns, should I rip up the vinyl to address this anyway?
Finally, if I am willing to pay Home Depot to do the installation, why wouldn't they offer to level the floor for me, and make a little more money on the job? But that is probably for another newsgroup...
Thanks,
Ben
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I had some spots that needed to be leveled, and I doubt if the company that I would of hired to do the install would of corredted the problem.
What I did was take a utility knife to cut the the vinyl where the floor needed to be corrected. It was an easy job as I used a sharpe stiff putty knife to scrape up the vinyl, and expose the plywood floor.
My floor settled over the suport beam in the basement, not the entire floor just in spots.
Some of the areas I corrected were 28in wide X 7ft long.I bought the leveler at Lowes came in 30lb bags if I remember right.
Tom

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