One way is to install php and wordpress on server following WordPress Windows 2008 Web Server R2 IIS 7.5 setup. Is it possible to reroute url like blog.yourcompanyname.com to another ip address and use linux host to do job?
How to add wordpress blog to Windows 2008 R2 site
you should be able to do this though DNS. If your server has a separate public facing IP address, just add a new record to yourcompanyname.com pointing blog to the IP address.