You can just use a function to post directly to the users wall. Just make sure that it is clear to the user that the button posts directly, perhaps use a dialog to get them to confirm they want to post. Here is the code I use:
/**
* Post to a friends wall
* @param msg Message to post
* @param userId Id for friend to post to or null to post to users wall
*/
public void postToWall(String msg, String userID) {
Log.d("Tests", "Testing graph API wall post");
try {
if (isSession()) {
String response = mFacebook.request((userID == null) ? "me" : userID);
Bundle parameters = new Bundle();
parameters.putString("message", msg);
response = mFacebook.request(((userID == null) ? "me" : userID) + "/feed", parameters, "POST");
Log.d(TAG,response);
if (response == null || response.equals("") ||
response.equals("false")) {
Log.v("Error", "Blank response");
}
} else {
// no logged in, so relogin
Log.d(TAG, "sessionNOTValid, relogin");
mFacebook.authorize(this, PERMS, new LoginDialogListener());
}
} catch(Exception e) {
e.printStackTrace();
}
}