Here's a starter - for which you'll need a Microsoft Compiler and SDK - and perl-5.10.0, though if you're using 5.10.1, I'm sure that could be worked around:
First, in the lanman source distro, insert this near the beginning of plmisc.h (just below the second line of that file):

// perl 5.10.0 build 10xx
#ifdef PERL_5_10_0

    #ifdef PERL_OBJECT
        #undef PERL_OBJECT
    #endif

    #define PERL_CALL_SINGLE
    #define PERL_CALL
    #define P_PERL
    #define P_PERL_SINGLE

#endif
[download]

Then set up the makefile to accommodate the existence of perl-5.10.0. This patch will do that:

--- makefile.orig    Tue Nov 24 11:03:55 2009
+++ makefile    Tue Nov 24 11:43:05 2009
@@ -6,6 +6,7 @@
 #
 # output directory for the appropriate build
 #
+outdir10xx=.\perl.10xx.release
 outdir8xx=.\perl.8xx.release
 outdir6xx=.\perl.6xx.release
 outdir5xx=.\perl.5xx.release
@@ -14,6 +15,7 @@
 # where is the perl appropriate directory (the include header files m
+ust reside 
 # in $(outdir)\lib\core)
 #
+perldir10xx=c:\_32\perl_vc7\5.10.0
 perldir8xx=c:\perl.8xx
 perldir6xx=c:\perl.6xx
 perldir5xx=c:\perl.5xx
@@ -36,7 +38,7 @@
 #
 # where is the platform sdk installed?
 #
-platformsdk=c:\program files\microsoft sdk
+platformsdk=c:\vsnet\Vc7\PlatformSDK
 #platformsdk=c:\microsoft sdk
 
 #
@@ -57,10 +59,11 @@
 !message
 !endif
 
-!if "$(cfg)" != "perl.8xx" && "$(cfg)" != "perl.6xx" && "$(cfg)" != "
+perl.5xx"
+!if "$(cfg)" != "perl.10xx" && "$(cfg)" != "perl.8xx" && "$(cfg)" != 
+"perl.6xx" && "$(cfg)" != "perl.5xx"
 !message
 !message Invalid configuration "$(cfg)" specified. Valid configuratio
+ns are:
 !message
+!message perl.10xx (for perl 5.10.0 build 8xx)
 !message perl.8xx (for perl 5.8.0 build 8xx)
 !message perl.6xx (for perl 5.6 build 6xx)
 !message perl.5xx (for perl 5.005_03 build 5xx)
@@ -74,7 +77,36 @@
 !error Invalid configuration specified.
 !endif 
 
-!if "$(cfg)" == "perl.8xx"
+!if "$(cfg)" == "perl.10xx"
+
+#
+# set parameters to build for (for perl 5.10.0 build 8xx)
+#
+
+# set the output directory
+outdir=$(outdir10xx)
+# where is perl installed? 
+perldir="$(perldir10xx)"
+# add per bin path to the path environment
+PATH=$(perldir10xx)\bin;$(PATH)
+# where is pod2html? 
+pod2html="$(perldir10xx)\bin\pod2html"
+# where is ppm? 
+ppm="$(perldir10xx)\bin\ppm2"
+# where do I find the perl include files and the perl510.lib?
+perlsrcdir="$(perldir10xx)\lib\core"
+# additional compiler settings
+cpp_add_flags=/D PERL_5_10_0
+# additional linker settings
+link_add_flags=perl510.lib
+# dll name to create
+dllname=$(prj).dll
+# prefix output tar.gz file
+targz_prefix=
+# tar.gz file directory
+targz_dir=mswin32-x86-multi-thread-5.10
+
+!elseif "$(cfg)" == "perl.8xx"
 
 #
 # set parameters to build for (for perl 5.8.0 build 8xx)
[download]

Your "perldir10xx" and "platformsdk" settings will almost certainly be different to mine - but the other changes should be applicable as is. (If you'd rather just get a copy of the amended makefile, /msg me your email address and I'll send it over - then you'd only have to make those alterations to "perldir10xx" and "platformsdk" and you'd be right to go.)

Then run nmake clean cfg=perl.10xx followed by nmake cfg=perl.10xx and see how it goes. If you're using MSVC++ 6.0, that might be all you need to do.
However, the build process doesn't succeed for me because my SDK (I have MSVC++ 7.0) doesn't have lmbrowsr.h and lmchdev.h - so I removed the call to #include those files from the files that try to #include them. (If you have MSVC++ 6.0, this may be unnecessary.)

In lanman.cpp, there are 4 occurrences of the comment // oops, not longer supported. For each of those occurrences, I had to remove the first line following the comment. Again, you may not need to do this if you have MSVC++ 6.0.

With that all done, the build ultimately fails with 4 "unresolved external symbols", which I haven't investigated. Which compiler do you have ?

Another possible solution - I see that there are ppm packages for this module for 5.6 and 5.8 at the bribes rep. The maintainer of that rep uses MSVC++ 6.0, so he may be able to build a 5.10 ppm, if approached. Yet another solution would be to install a perl-5.8 (as a second perl installation) just so you can make use of the existing ppm.

It's a pity that the source for such a useful module (by all accounts) is in such a poor state.

Cheers,
Rob