As I would like to use PowerShell integrated with the visual studio command prompt, here is one nice solution for this.
http://blogs.msdn.com/b/ploeh/archive/2008/04/09/visualstudio2008powershell.aspx
The basic idea is that we need use the Set-Item to set the environment variables parsed from the = in the original bat files.

Today I want to check whether the Windbg is installed on the target machine with expected version, and if not, install the correct version with Powershell. It turns out that Powershell is really powerful to do such things.

$dbgApp = get-wmiobject -class "Win32_Product" -namespace "root\CIMV2" | where {$_.Caption -like '*Debugging Tools for Windows*'};
if ($dbgApp -eq $null -or !$dbgApp.Version.StartsWith("6.13"))
{
    msiexec /passive /i D:\Debug\dbg_amd64.msi;
}