The Win32 implementations of Perl and Python more-or-less build in direct access to all of Microsoft's Win32 API(s).
[more detail - what kind of interface is this?]
Tcl does not, a crippling disadvantage in some contexts.
[What is the proposed solution here then?]
However, Tcl has its own approaches, including ffidl ...
The no-charge version of bcc55 [...] includes a no-charge version of a reference to the Win32 API [...].
PT The entire Win32 API documentation is available from http://msdn.microsoft.com/library/
Windows API Reference [L1 ]
BR Note that the docs at the MSDN site do not include the actual values of manifest constants. This is a major source of grief for all Open Source projects dealing with the details of the Windows API. One could consider Microsofts actual headers as complementing the documentation in this regard, the headers are part of the SDKs which are available free of charge. But most projects fear to use or even just look at those because of possible copyright issues.
The TWAPI project intends to remedy this by providing access to Win32 API's (NT based platforms, not Win98) not directly available from Tcl.