TCH should be able to add a cname record for you to point to another ip address for a sub domain. I would not see where that would go against TCH's TOS agreement. Otherwise you would have to do what they were talking about and do the mod_rewrite to point to the windows host.
Otherwise what you could do it what I have done. I use dyndns.org to host my dns, and then I can point the different parts of my domain to different places. I have a sub domain xxx.**** pointed to a server at my house, and I have ohter sub domains pointed other places.