i’ve used msvc to debug externals when they cause a crash… there’s that "kill program or debug" message box that pops up, which brings you to another one that allows you to attach an instance of msvc. i’m not sure how to get it to debug without a crash though.
my guess is that stuff like printf wouldn’t really work there anyway… i’m not sure that the debugger connects to the max standard i/o streams, which it would need to do for that stuff to work.
in a worst case scenario, you could just use a log file…

my approach to that kind of thing has always been a combination of wrapper functions and variadic macros, which allow me to switch the debug output from one method to another simply by changing a single #define statement…

something like…

void _dbg_print_log(const char *fmt, …)
{
print message to log file
}

void _dbg_print_max(const char *fmt, …)
{
print message using post()
}

#ifdef DEBUG_OUT_MAX
#define dbg_print(fmt, …) _dbg_print_max(fmt, __VAR_ARGS)
#else
#define dbg_print(fmt, …) _dbg_print_log(fmt, __VAR_ARGS)
#endif

i’m not sure about the syntax of the macros… i generally end up spending a few minutes looking at reference materials for stuff like __VAR_ARGS (which i’m sure is supposed to be something else)