Mobile Tools: How to use URL redirection with multiple subdomains

Issue Summary

I would like to redirect from multiple subdomains to multiple mobile subdomains.

I want to use redirection so that Drupal caching still occurs, but I need to preserve the subdomain information/context.

eg
www.sub1.example.com to m.sub1.example.com
www.sub2.example.com to m.sub2.example.com
www.anything.example.com to m.anything.example.com

The sub part currently comes from using Organic Groups with Subdomain module.

The main use of the redirect is to change the theme, but other things like selection of download file format and media player will follow.

I realise that this is similar to using MT with Domain (domain access) module: (http://drupal.org/node/488780), but I thought it was sufficiently different to raise a different issue.