You only need to do the following guide if shrinking the ISO's
1. launch the multigame ISO creator 3.5.4f+
2. select the region of the ISO to be created (USA, PAL, JAP)
3. select the games to be placed in the multigame ISO, using the "Add ISO" button
4. check the shrink box for each game
5. look at the disc icon in the lower left corner, if the ISO is larger than 4.37GB then remove one of the games from the project
6. now create the image
7. after the images have been shrunken, there will be a prompt to delete the shrunken images, select NO
8. exit the multigame ISO creator
9. you will now notice that a folder named "Compressed Images" and the multigame ISO have been created.
10. delete the multigame ISO that was created, you need to run FSTFIX on the compressed images.
11. copy the "wiped_gcm_fixer_v1.5f" archive (from the download) to the "Compressed Images" folder, right click the archive and select extract here (you will need wirRAR or simular program installed)
12. drag and drop a compressed GC ISO on the FSTFIX application and wait for it to complete the process, the FSTFIX dialog box will disappear when completed, and your ISO will be fixed for a multigame ISO.
13. repeat step 12 for each ISO to be added to the multigame ISO.
14. now lauch the multigame ISO creator again and load the fixed compresses ISO images from the Compressed Images folder.
15. once the images are loaded, select the region of the ISO you are creating, no need to compress the image (it's already compressed), now click the "Create MultiGame ISO" button.
16. Right click the image that was created and select "burn using IMGburn", you need IMGburn installed for this.