There may be a faint hope for you:

  Locally applied patches:
        ActivePerl Build 629
  Built under MSWin32
  Compiled at Mar 26 2003 18:19:43
...
type:cv  -libpath:"\public\ratlperl\5.6.1_AS629\lib\5.6.1\MSWin32-x86-
+multi-thre
[download]

This suggests to me that your Rational Perl is a rebranded ActiveState Perl (build 629). So you might be able to just download the PPM and copy the files into the appropriate positions, or maybe it even comes with its own PPM.

You won't be able to "just" copy some files and copy some random DLLs downloaded from the internet and expect it to magically work. There are ways to use a different toolchain than what was used to compile your Perl to compile extensions, but the preferred and sane way is to use the build environment that was used to build your Perl. In your case, that would be Visual C 6.