For my 10th grade Biology class, I do not have the equipment for Gram staining. I found a neat virtual lab by NMSU and created a WebQuest that takes students through the process of the Gram stain. After, I have the students look at various slides that I have of already-stained bacteria and use the correct terminology to describe the bacteria (bacillus, coccus, strepto, diplo, etc.).
The lab is in Word, so if you don't have the materials to do the physical portion of the lab, nix it! (or have students find pictures of bacteria under the microscope, perhaps).
Just a word of caution: if students do not finish the Gram stain virtual portion in one sitting, there is no way to pick up where you left off when you begin again. This can be frustrating to some students, so just make sure that they can get it done all at once!
My diligent students complete the virtual + microscope portions in one period (40 minutes). Slower students will likely take closer to an hour to complete the entire lab.