OK, I noticed you're probably using another version of wxWidgets (2.6.2?), because I'm using 2.6.1 and didn't need any fix to get it working, but if I apply the suggested fix (cast to unsigned long) it gives the error:
cbprofilerexec.cpp:176: error: `class wxColour' used where a `long unsigned int' was expected
EDIT: Or something went wrong with your setup because there isn't any constructor of wxColour which accepts unsigned longs:
wxColour()
Default constructor.
wxColour(const unsigned char red, const unsigned char green, const unsigned char blue)
Constructs a colour from red, green and blue values.
wxColour(const wxString& colourNname)
Constructs a colour object using a colour name listed in wxTheColourDatabase.
wxColour(const wxColour& colour)
Copy constructor.
And wxListItem's SetTextColour() only accepts wxColours:
void SetTextColour(const wxColour& colText)
Sets the text colour for the item.