There are four main color modes for a Tiff file. BW, Grayscale, RGB and CMYK.
If the Tiff file you have or are creating is Black and White (or is going to be a Spot Color,) then the process is simple. In Photoshop, create or open the file, convert it to Bitmap Mode (under Image>Mode) and save it as a Tiff. When you Place it in Pagemaker the white areas will be transparent and the Black areas won't (and you can assign any color you want to the image.)
If the file will be in a different color mode, you'll need to create a clipping path. In Photoshop, draw a path around the object you want to keep. Tighten up the path so that no background pixels show through. Save the Path in the Paths Palette by double-clicking on it and giving it a name. Then, in the Paths Palette's Menu, select Clipping Path and choose the path you've created. You can then save the Tiff file as normal, place it, and voila, an object with a transparent background.