no, you won't be able to use "\\" in XamlPath.
And XamlPath needs to follow a liner path. You have to traverse all nodes that lead up to a specific child element. It's best to combine XamlPath with a different Find Logic that gets you to the desired "starting" point, so to say.
For instance if you're looking for the first cell in a Grid named "MyGrid" here's what the Find Expression might look like:
We use the first part of the statement to get to the appropriate reference node. From there we use XamlPath to point to a specific element from its children.
I hope this helps.
the Telerik team