How do I specify MSBuild to execute command-line calls in ascii not unicode

Question

I'm attempting to target VC7.1 (visual studio 2003 sp1) from Visual Studio 2010.

I'm so close to setting it to work. But when I build, I get this error.

1>------ Build started: Project: AnExample, Configuration: Release Win32 ------
1>  Microsoft (R) 32-bit C/C++ Standard Compiler Version 13.10.6030 for 80x86
1>  Copyright (C) Microsoft Corporation 1984-2002. All rights reserved.
1>  
1>  cl ÿ_/
1>  
1>cl : Command line warning D4024: unrecognized source file type 'ÿ_/', object file assumed
1>  Microsoft (R) Incremental Linker Version 7.10.6030
1>  Copyright (C) Microsoft Corporation.  All rights reserved.
1>  
1>  /out:.exe 
1>   ■/ 
1>LINK : fatal error LNK1181: cannot open input file ' ■/.obj'

I know this is unsupported but I thought I'd give it a go.

Does anyone know how to force the output from msbuild to be ascii or if this is the problem? There were some errors like this years ago related to the DDK acorrding to some other forums.

Thanks.

edit: so I noticed that UseUnicodeResponseFiles is missing in 2010. Any idea how to add this property back? MSBuild isn't easy to learn. I also can't determine from the msdn docs whether this property is supported and just missing or not.