Yeah, ActiveState appear to still use Visual Studio 6 to compile ActivePerl:

c:\>perl -V
Summary of my perl5 (revision 5 version 8 subversion 8) 
  Compiler:
    cc='cl', ccflags ='-nologo -GF -W3 -MD -Zi -DNDEBUG -O1 -DWIN32 -D
+_CONSOLE -DNO_STRICT -DHAVE_DES_FCRYPT -DNO_HASH_SEED -DUSE_SITECUSTO
+MIZE -DPERL_IMPLICIT_CONTEXT -DPERL_IMPLICIT_SYS -DUSE_PERLIO -DPERL_
+MSVCRT_READFIX',
    optimize='-MD -Zi -DNDEBUG -O1',
    cppflags='-DWIN32'
    ccversion='12.00.8804', gccversion='', gccosandvers=''
    intsize=4, longsize=4, ptrsize=4, doublesize=8, byteorder=1234
    d_longlong=undef, longlongsize=8, d_longdbl=define, longdblsize=10
    ivtype='long', ivsize=4, nvtype='double', nvsize=8, Off_t='__int64
+', lseeksize=8
    alignbytes=8, prototype=define
[download]

12.00.8804 is VS6

I use the VC++ Toolkit for compiling modules. On the whole this works. Of course the VC++ Toolkit is no longer available.

A possible solution may be to compile Perl yourself using the newer Microsoft tools.