@tobyscarer,
Hi tobyscarer.
It's hard to work with a dog who's had a rough start but it's definitely worth the effort.
As Setanta has suggested, you can try lifting him wrapped in a towel to take him outside. Make sure you've got either pee pads or newspaper near where he sleeps, so he can go there if he was ever paper trained.
Do give him some time though before you try to move him - he may decide on his own that he's ready to go out. Try and stay near him so you can watch him for clues.
Has he eaten yet or had anything to drink? try to set up a routine for both of you where he feeds/eats and is taken outside not too long thereafter.
Does your little guy have a crate he can go to if he is stressed? or maybe something he can get underneath - like he's in a cave? that may help him get comfortable.
When I adopted the dog Set talks about in his post, I went through a dozen or so sweaters the first week I had her as she was so dirty and stinky - but still liked being held. I'd pick her up, give her a snuggle, take her out - bring her in and throw whatever I'd been wearing in the wash. Due to her stress, I couldn't clean her right away. She also did submission urination so I couldn't come directly into the house for close to half a year - she always peed when she first saw me when I came home. We set up a routine where I opened the door, set my feet apart, she came out and peed on the porch between my feet and then we went inside.