Yes. If you have the following menu callback prototype:
void CVICALLBACK ConfigTestCallback (int menubar, int menuItem, void *callbackData, int panel)
then you can call it directly as follows:
ConfigTestCallback (menubarHandle, ITEM_NAME, 0, panelHandle);
Provided you have the menu bar returned by GetMenuBar() and the panel handle returned by LoadPanel as well as the ITEM_NAME, the name you gave to the menu item in the UIR editor.