EDIT:
On second thoughts, you are right.
Just a little change
ShellExecute(GetDesktopWindow(), "open", "c:\\someFolder\\myFile.pdf #page=4", NULL, NULL, SW_SHOWNORMAL);
Just add a space, cause page=4 is an argument.
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I don't know if there are anyreal ways to do it. But how about triggering some keyboard inputs with keybd_event()
All you have to do is Ctrl+Shift+N to open the "go to page" dialog box. and then the input the number 4(say) and also "Enter" with the same function. Before all this you have to give time for the pdf to get opened and become active(You may have to use the function Sleep())
You can get the complete set of Virtual key codes in msdn
Hope it helps