That's the 'Object' command in 2003 on the 'Formatting (Form/Report)' toolbar. You will have to add this command manually.
From Microsoft Online:
1. Click the Microsoft Office Button, and then click Access Options.
2. Click Customize.
3. In the Choose commands from list, click All Commands, and then find the command you want.
In your case, you are looking for the 'Object' command.
If you ever have trouble finding anything else, here's an interactive tool that Microsoft put together that let's you find things in 2003 and it gives you instructions to find it in 2007. Click on Start Guide to begin the interactive tool.
Link --
Interactive: Access 2003 to Access 2007 command reference guide 
