I don't have any tips for making the smell go away immediately, but I can say that about 7-10 days after purchasing 8 of these 4'x6' mats that the 'chemical smell' did finally dissipate. I say stick it out...it should get better.
I don't have the stall mats, but something I got from Jesup Gym (4'x6'x1/2", weigh about 70lbs each). They stunk to high heaven when I first unrolled them and put them down on the floor, but I think within a week they stopped stinking. I don't smell the rubber smell in that room at all any more.
If you want to hasten getting rid of the smell, make sure you have a fan going and some cross-ventilation to blow unstinky air in and stinky air out.
I purchased one of those 4X6 stall mats last May and like yourself, I was tempted to get rid of it because the smell was so bad. The smell did dissipate over time and now it's pretty much gone. Initially, I found that spraying some Febreeze made the smell more tolerable.