Honestly, I wish there was ANY target you could macro ground targets onto, let alone waymarks. It'd be great to be able to target the main tank and drop a Shadow Flare centered on her. Mouse targeting is awkward and controller targeting is worse; the only time a player should be required to do it is if there simply aren't any targets in the area where you want to drop the aoe.

It could be that this feature exists in the game, but if it does I haven't figured it out.