Yes, if you have an active DL account you can put your Amex points in to DL and then transfer them into HHonors. In theory. DL may not permit non-flight miles to be converted this way, but I don't believe this will be a problem. However, if you don't have a DL account, you'd have to open one and make at least one DL metal flight to activate the account before moving Amex points into it.