Is it possible with a control key, e.g. CTRL+A to setcursor on absolute address (second column, current line) of a table "All items" of an SAP order?

Yes, use the following coding in your script: 
Pushbutton (toolbar) "Material column" process="va01_setcursor2.txt" "Ctrl+F12"
if V[NewCursorPosition]
   SetCursor "&V[NewCursorPosition]"
   Set V[NewCursorPosition] ""
...and the InputScript "va01_setcursor2.txt":
Set V[NewCursorPosition] "cell[All items,2,&V[_tabrow]]"
With Ctrl+F12 the cursor is now set into the Material column. Previously Ctrl+A could not be assigned by GuiXT, but we have added this to the version (2002 Q3 11).
This solution is not a local frontend action. The GuiXT "Tab" command would provide an alternative solution for fast data entry.