Add a CNAME for www.your-old-domain.com pointing at ThreeZeroOne.com
Add a TXT record for threezeroone.www.your-old-domain.com containing either:
redirect all www.yournewdomain.com
or
redirect relative www.yournewdomain.com
There is no Step 3.
'relative' means /something will point to /something on your new domain, 'all' means everything will go to the host/path specified in your TXT record.
It works with any sub-domain, it doesn't have to be 'www'. Apex domain names are currently not supported but will be in the future. You can use a Route53 ALIAS record pointing at aa1627dc0106c11eabc9a026e996c53b-514856871.eu-west-1.elb.amazonaws.com in the meantime.
Currently doesn't support SSL but totally could if anyone wants it to - tweet us @parallax
Made with love by Parallax. Doesn't come with a warranty but we will look after this service and won't do horrible/nasty things with it.