SendKeys

Symbols can be added to a custom quote page using SendKeys to accomplish the task as if typed at the keyboard.   This small script will illustrate the principle.

begin
  Quote(eCustom);
  SendKeys('{alt}QA');
  SendKeys('US1H{return}');
  SendKeys('IBM{return}');
  SendKeys('F{return}{return}');
end;

The  {alt}QA  manipulates the Quote page menu to select the Add Symbol menu item.
Symbols are entered and the return key pressed to add the symbol to the quote page.
The last symbol entered has an extra return to put the Add Symbol input box away.