Probably the best thing would be to negotiate a rate in Euros. As far as their accounting is concerned, it wouldn't be much different from using a local freelancer. They can send you a check in Euros and you can have it deposited to a US bank, although you'll have a poor exchange rate and some risk from currency fluctuations.
I've never worked with a French company, but I do know that for English companies, you need to be represented by a UK-based proxy (because a lot of consultants moved their official locations to tax-free countries).
You might want to get some form of payment up front. Not only does this force them to iron out any kinks in the payment process, you are at lower risk from getting stiffed at the end. Really, there's almost no easy way to get a foreign company to pay you if they decide to skip out on the bill.