Change default path for custom templates

I want to change the default path middleman uses to search for a custom made template. I’m using windows 8 x64 and when I run

middleman init D:\folder --template=custom_template

I need to have custom_template located in

C:\users\username\.middleman

As a rule, I don’t keep any type of personal data in the windows partition (nor should anyone else).

I’ve also tried using

--template=D:\path\to\template

but that doesn’t work.