You might try ActiveState 5.12 and see if you have the same issues. I believe 5.14 is the first to make that macro return an r-value. You will also need to search the code for the string #pragma comment(lib, "perl510.lib") and change it to the version you end up using. There are two places that need to be changed.
Some have reported that Strawberry Perl 5.10 worked for them, although I have not used it. You can get it here:
http://strawberryperl.com/
I haven't had to compile with the newer version of zlib that renamed the files yet. If I had to I'd probably text replace "zlib.lib" to "zdll.lib" in all the *.vcproj files under the EQEmuServer directory and hope for the best. Kind of a pain though because if someone changes one you'll have a conflict when you refresh from SVN.
Other options include working some Google-Fu to find an older version before the rename, or some people have said that just renaming the new file to zlib.lib worked for them.
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