You can use pInvoke and a native call such as the following. This doesn't seem to have the 32 / 64 bit limitation (at least in my testing)
Here is the code
using System.Runtime.InteropServices;
[DllImport("Kernel32.dll")]
static extern uint QueryFullProcessImageName(IntPtr hProcess, uint flags, StringBuilder text, out uint size);
//Get the path to a process
//proc = the process desired
private string GetPathToApp (Process proc)
{
string pathToExe = string.Empty;
if (null != proc)
{
uint nChars = 256;
StringBuilder Buff = new StringBuilder((int)nChars);
uint success = QueryFullProcessImageName(proc.Handle, 0, Buff, out nChars);
if (0 != success)
{
pathToExe = Buff.ToString();
}
else
{
int error = Marshal.GetLastWin32Error();
pathToExe = ("Error = " + error + " when calling GetProcessImageFileName");
}
}
return pathToExe;
}