You would need to use absolute urls and in place where you cannot use absolute urls , you would need use a js script to check the url and then redirect if not using domain.
More information :
https://www.youtube.com/watch?v=M2oIpq2gFP8
With shop process , you would need to modify the layout code :
Sorry but there is no direct way other than custom solution.
Thanks,
Sanjit