I have reached the point in the disassembly of my 68 Coupe where I need to remove the subframes from the body. Considering the jack points are on the frame members, how are you supposed to support the body when the frames are off? I do not have a rotisserie, and I am replacing floor panels, so I cannot use the normal connection points the frames use. Any advice or recommendations?

You could build a frame cart. see attached
What is the condition of the body? Do you have pics?

Can use the frame mounting locations on the firewall torque box? If so, I used a 4x4 cut to length and drilled to allow a longer bolt. I had to angle cut the ends to clear the contour of the firewall. Then I mounted the 4x4 across the firewall of the car. Jack stands or a jack can be used then and the sub frame is not an issue anymore. If you plan to replace any firewall section near the floor, this will not work.

I just support mine on jackstands by the rocker panels when I separate subframe from body. A couple small strips of lumber...like foot-long cut strips of 3/4" plywood...laid on each side of the pinch weld, will distribute weight along the rocker and prevent any damage to the pinch welds. The location of support will gives you full access to replace the floor and to reach all the subframe bolts.

Remember a body without an engine/trans, subframe, suspension, interior, etc is very light in weight...so there is little fear of doing any damage to anything if you're just basically supporting the weight of the firewall and floors...and dash and doors if still attached. So you can pretty well use any solid bit of metal that you won't be cutting out to support the front of the unibody.

Frankly it will be light enough in weight that your biggest concern really needs to be avoiding leaning/pushing/beating hard enough on the body while working on it that it starts to shift on your supports and possibly fall off of them. When doing such work I take extra steps to actually attach the top of each jack stand to the chassis. All kinds of creative ways to do this...screws/bolts/u-bolts/lumber, tie them together with wire, even tack the car and jackstand together with a welder or whatever...but with some method I just set it up so that in the unlikely (but possible) event the body of car gets forcefully shoved any direction, I want the jackstand to harmlessly slide on the floor along with the body, and NOT the body to slide relative to the top of the jackstand...which could cause serious damage/injury/death.

Such unwanted movement is ESPECIALLY easy/risky if you still have the rear axle in the car and the rear tires are free to roll...allowing the car to pivot. If this is the case also use FOUR very solid wheel chocks on the rear wheels. I'm not sure how far you're disassembling the car, or how high you intend to raise it up in the air for whatever you're doing here...

I made mine with 2x2 square tubing and some heavy duty casters. Pics are on my photobucket.

I have adjustable connector bars and wheels for it, it also has slides for different width cars and adjusts up to 4 ft high. Not completely done with it yet but it will stretch to fit when sub frame is on also