Is it possible to import BI Publisher subtemplates using an environment variable to identify the imp

When developing locally, I load subtemplates using this type of syntax:

<?import:file:///C:/temp/MySubTemplate.rtf?>

However, on the server, I need to use

<?import:file:///D:/subTemplates/MySubTemplate.rtf?>

Is it possible to use an environment variable such as

set SubTemplate_Path = c:/temp

and then use that environment variable to identify the path in the import statement like this:

<?import:file:///${SubTemplate_Path}/MySubTemplate.rtf?>

Thanks.