I saw the MS VC7 compiler offered, downloaded it, posted the news, downloaded the necessary libraries, and tried to build Perl with it. I had to patch Makefile so that the build process for miniperl works:

• msvcrt.lib seems gone, so I substituted libc.lib for that
• The delayed loading of winsock.dll doesn't seem to work, so I removed it
• The compiler wants a special command line switch, /ML, if it should link to libc, so I changed that too.

This is the diff of my 5.9.1 Makefile, as downloaded from perl.com :

< DELAYLOAD     = -DELAYLOAD:wsock32.dll -DELAYLOAD:shell32.dll delayi
+mp.lib
---
> #DELAYLOAD    = -DELAYLOAD:wsock32.dll -DELAYLOAD:shell32.dll delayi
+mp.lib
> DELAYLOAD     =
347c348,349
< LIBC  = msvcrt.lib
---
> #LIBC = msvcrt.lib
> LIBC  = libc.lib
356c358,359
< OPTIMIZE      = -Od -MD -Zi -DDEBUGGING
---
> #OPTIMIZE     = -Od -MD -Zi -DDEBUGGING
> OPTIMIZE      = -Od -ML -Zi -DDEBUGGING
360c363,364
< OPTIMIZE      = -MD -DNDEBUG
---
> #OPTIMIZE     = -MD -DNDEBUG
> OPTIMIZE      = -ML -DNDEBUG
396c400
< CFLAGS                = -nologo -Gf -W3 $(INCLUDES) $(DEFINES) $(LOC
+DEFS) \
---
> CFLAGS                = -nologo -GF -W3 $(INCLUDES) $(DEFINES) $(LOC
+DEFS) \
569c573
< # We need this for miniperl build unless we override canned
---
> # We need this for miniperl build unless we override canned
788c792
<               "ccflags=-nologo -Gf -W3 $(OPTIMIZE:"=\") $(DEFINES) $
+(BUILDOPT)"       \
---
>               "ccflags=-nologo -GF -W3 $(OPTIMIZE:"=\") $(DEFINES) $
+(BUILDOPT)"       \
820c824
<           perlglob$(o) setargv$(o)
---
>           perlglob$(o) $(SETARGV_OBJ)
[download]

Miniperl builds OK, but when I do nmake test, I get an access violation in the newly created perl.exe for some instruction at 0x77892373, which tried to read memory at 0x000000000f - so I did something wrong while slashing around in the Makefile. But what?

Update: Rephrased the last paragraph