Good time of day for all!

I have some troubles, and i hope you guys can help me. I search google, but did not find valid answer for my question.

I want to open alternate file streams. If i write something like
I receive expetion. It says, that file path in this format is not supported in .NET.

Good, i found very simple solution, using CreateFile API and contructor in IO.FileStream class, that receive windows file handle.

I have to use this code in ASP.NET pages, located in the remote server. And, it seems to me, hosting's security policies forbids applications to use Windows API.
Anyway, i recieve <access denided> error, when use any Windows API on the ASP.NET pages, located on the hosting. I do not receive this errors on same code, if it executes on my local machine.

So, i want to ask you: How can i open Stream object for the alternate file stream, without using Windows API?