Different application filepaths for TestedApps

There's not EXACTLY a way of importing a TestedApp in like that.  However, a couple of things:

1) TestedApps is an object in TestComplete with a method called "Add" where you can add a tested application on the fly.  Sample code is at https://support.smartbear.com/testcomplete/docs/reference/project-objects/items/tested-apps/testedapps/add.html along with all sorts of other documentation.
2) TestedApp is an individual item within the TestedApps collection which you can set a number of properties on as well. (https://support.smartbear.com/testcomplete/docs/reference/project-objects/items/tested-apps/testedapp/methods.html)

3) There is an object called Storages which has an XML capability.  (https://support.smartbear.com/testcomplete/docs/testing-with/advanced/working-with-external-data-sources/xml.html#Storages) 

Combine these three different pieces and you can write code to do EXACTLY what you want: read configuration information from an XML file into the project and use it to launch your tested application regardless of machine.