Please provide more details: what is the API function, pointer to what kind of data you need etc.

It is easy to provide the pointer to a FoxPro string.
For instance in the following code a pointer is used to return data from API function:

DECLARE INTEGER GetWindowsDirectory IN kernel32;
	STRING @lpBuffer, INTEGER nSize

cBuffer = SPACE(250)
nResult = GetWindowsDirectory(@cBuffer, Len(cBuffer))
cBuffer = Left(cBuffer, nResult)
? cBuffer

Check http://www.news2news.com/vfp for more code samples using Win32 functions in Visual FoxPro.