Need a PRECISE HIK T-Pose for applying Rokoko mocap

I’m using Character Creator 3 for a character, Rokoko for mocap, Motionbuilder for cleanup, and ideally UE4 for final animation. (This is working great with iClone, but since iClone can’t use Rokoko facecap it will eventually have to go through UE4.) I’m able to get everything into and out of CC3, Rokoko, and Motionbuilder, but the problem with UE4 seems to be the A-pose versus T-pose, since MB and Rokoko spit out T-poses on an HIK skeleton. I’ve tried manually t-posing, and even found an alleged t-pose online, but neither of those exactly match the MB HIK T-pose, so the thumbs and fingers get really screwy (some other joints, too). How can I get an ACTUAL and PRECISE T-pose to (I presume) import as a pose asset to my character’s HIK skeleton and then hopefully retarget my cleaned up Motionbuilder mocap on that?