Tip: How to copy your XCode Provisioning profiles across to another computer
How to export/copy your existing XCode Provisioning profiles/certificates across to another computer
If you want to keep your existing provisioning profiles and signing certificates, but use them on a different computer, you can in fact do it all in XCode, rather than having to tinker with Keychains. All you have to do is go in XCode to Device Organizer and select your team, then click Export. Give your exported credentials and a name and password to authenticate, then pass it along to a shared drive/folder, to copy across onto your other machine, by coming to this same section and selecting Import.
See, so easy I feel guilty even putting this up a a post.