All I can offer is untried opinions. Hammer a very sturdy wooden pole or stake into the ground at the base and twine the vines around to 4 feet high. Use binders twine or cotton thread to tie the vines to the stake. The vines should gain enough strength to hold the top up by the time the stake rots and the twine should rot before it cuts into the vines. Annual, brutal pruning will be need to keep the plant into a tree shape. I can only guess that this should be done after the Spring bloom but before July ends, so that next years buds can form. Several are in my neighborhood, the most notable is a 10 ft. diameter white one that has branches solid with flowers, branches and flowers trailing almost to the ground below.

I pretty much did as bogturtle recommeds, trained mine up to about 5 feet of trunk then trimmed the top to encourage branching. I pruned mine late winter, each branch back to about 3 sets of buds, then as needed during the rest of the growind season to keep it in shape. When a week or so would get by with out pruning it would look like a giant sea anemone, with arms waving all about! When it bloomed it was gorgeous. I had to have it removed eventually because of the attraction wasps had to it. Just keep in mind that even those trained as standards will eventually need support again to stay upright, they seem to want to lean after a while (about 10 years)