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 [...].
The TWINE project (coming to an open source repository near you) intends to remedy this by providing access to Win32 API's not directly available from Tcl.