I dont see how you could use a trueing stand with the drive side because the rim has a keyed washer welded where the bearing would go. will probably just use a zip strip.
I'm still not understanding, can you post a picture maybe? There has to be a way to mount the thing in the stand. Just put something in there to replace the axle on the stand. You could still get fairly close with a zip tie on one side of the trike rear if you had to.
This is the way I do mine. I flip the trike upside down, so the handlebars rest on the ground (for stability). I then stack some properly sized stuff under the rear housing, to hold the wheel at just the right height, which allows me to slide my truing stand into a usable position.
Normally when doing a trike rim I drop it off at the local bike shop and pay them $15 to figure it out. He's got some sort of attachment so he can true trike rims in his stand.