используй Data, ну например так
unit HiAsmUnit;
interface
uses kol,Share,Debug,Windows;
type
THiAsmClass = class(TDebug)
private
protected
public
onTX:THI_Event;
TX:THI_Event;
procedure doTX(var _Data:TData; Index:word);
end;
implementation
procedure THiAsmClass.doTX;
begin
_hi_CreateEvent(_Data,@onTX,ReadData(_Data,TX));
end;
end.