I'm having a go at Soya beans and Sugar Snaps this year... I assume the Sugar Snaps will need something similar to normal peas? And Soya beans... I don't know how big they get and if they're climbing or bushy... these are the ones I'm growing http://www.thompson-morgan.com/seeds1/product/611/1.html it doesn't mention canes or anything in the sowing and growing instructions.
I grew some last year which claimed to be 'self supporting' They had to be grown quite close together and clung to one another as they grew.
The seed packet should come with instructions
The packet doesn't mention anything about support either... so I'm guessing they don't need any then, or as you suggested, they support themselves (planting is 6 inches apart).
Thanks :)