I'm a no longer practicing, Independent "VERY SMALL" Travel Agent who "signed up" with AMEX many moons ago to offer clients CPP benefits. I've procured the $200/$300 benefit on several occasions BUT NOT the "Extra Membership Rewardsยฎ points" (I think you need your own "Merchant account" for that.
It wasn't difficult, didn't cost me anything, & I didn't have to prove anything to AMEX other than signing up to offer it. It was though VERY HARD to find out how/where to do so. My perseverance paid-off as I'm getting the OBC these days :-)
I suggest asking point-blank if the agency/agent is geared up to offer CPP. There must be others like me, out there, somewhere.