First I am not an expert by any means. I just know a little bit from trial and error and lots of reading. Lots and lots of playing around. I hope you will give this a try and have fun with it. Most of all I hope it actually works for you!
I am using Photoshop cs5 but it works pretty much the same with earlier versions. How early I don’t know. Sorry I can’t remember what I used to have.
Open all of the photos you want to use and size them all the same, label and save them.
Open them all up and open a new blank canvas on white the same size as your photos.
Using the move tool, move all of your photos onto the white canvas. One right on top of the other.
Under Windows open Animation. It will open with a photo already in the first frame. In the animation frame click the box for a new frame then click shut all of the eye icons (in the layers palette) except for the next photo that you want to open in the frames. Continue in this manner until you have all of your photos used. When you click for a new frame it make a duplicate but not to worry the new photo will take it’s place.
In the animation frame under each photo you will see 0.sec. click on that and choose which speed you want for each photo. They can be all the same or different. Just play with it.
When you are happy with the timing click save for Web and Devices and save it as a GIF.