To answer the OP:
“would ILLUSTRATOR CS4 be a good enough program to use for my project?”
Yes this program is good enough for your project. Illustrator is an excellent tool for creating both techpacks and product renderings, but like anything you will need to become a master of your tools. Others have recommended also using Photoshop. While Photoshop is nice you do not need it. With enough skill you can create photo renderings solely using Illustrator.