I wrote a guide for those of you still looking for a solution.
NOTE: This guide assumes you know how to navigate your backend using either an FTP program or CPanel, Plesk or a file manager that you can access directories with. This practice was done using Joomla 1.5.22, JComments 18.104.22.168 & Phoca Gallery 2.7.6
I posted some questions on Joomlatune asking for help with making JComments and the JComments module, but I never got any help. I do understand that their is only 1 single developer, so I don't wish to make it seem like he isn't helpful because he is. Without him we would't have such a wonderful Component. I'm going to explain what I wanted out of JComments, the problems I ran into along the way and last, the solutions to those problems.
Installation of JComments is simple enough so I won't wast your time talking about that. I will skip to what I think most people have a problem with right off the bat and that is the "JComments Latest" module, which allows people to see latest comments, rather it be from a Joomla article or a Phoca Gallery image. I will use my website as an example. I wanted to have members post comments on my Phoca Gallery images, and when they did, it would automatically show up in "JComments Latest" module with linkable text to the commented image. (When you click on the 'Comment' it would take you to the Image that was Commented.)
The hardest part was figuring out that I needed some files from the Phoca website that allowed Phoca images to be commented with JComments. It seemed as if the developers always knew what they needed to do in order to fix something, but they only helped when they were asked. This took to much of my time. I realized you need 2 important files in order for JComments and Phoca to work flawlessly.
The files you need can be downloaded on the Phoca website HERE. You are looking for, "Phoca Gallery - JComments Plugin Files:" The actual file is a .zip file and is named, "com_jcomments_phocagallery_plugins.zip".
These files are .php files that you need to put into a certain directory, so pay attention.
1. After downoading the "com_jcomments_phocagallery_plugins.zip" file, make sure and extract it first on your computer. After extracting, you will see only 2 files, one file named, "com_phocagallery_images.plugin.php" and the other named, "com_phocagallery.plugin.php".
2. Take both of these files and copy them into the directory, "/components/com_jcomments/plugins/". Not "/administrator/components/com_jcomments". If you are promted to overwrite previous .php files, overwrite them. You want to overwrite them as this is neccessary. I suggest to rename the original .php files so that way you can revert back to them if you run into any problems, although the chance of you having additional problems is .000000000001 to none because they were written by the developers anyway. Once the .php files are in place you should now be able to comment Phoca Gallery Images.
3. Next is to go into the "Latest Comments" Module (Or whatever you renamed the module), and have a look in the parameters. 2 very important steps need to happen here. First is to set "Enable Mambots" to "Yes." Second it to tell JComments where to pull the comments from. If you want the 'Latest Comments' module to show comments from Phoca, you need to change the "Source" Parameter. Inside the 'Source' text box, erase everything inside, then add this without quotes, "com_content,com_phocagallery,com_phocagallery_images". This tells jcomments to get comments from joomla Articles & Phoca Gallery images.
To make the avatar show up in 'JComments Latest', you have a few more steps to do.
1. Make sure you have installed the plugin that supports avatars/gravatars. If you don't have it you can find it HERE. Your looking for "JComments Avatars 3.1 for Joomla 1.5". Will be under "JComments Plugins" in green bold letters. If you already have already installed 'JComments Avatars 3.1 for Joomla 1.5' plugin, go to the plugin's parameters in (Extensions>Plugin Manager>JComments - Avatar).
2. In the plugin parameters, change "Avatar Source" to whatever third party component you are using. For me it was Community Builder. If you are using Gravatars, set to gravatar, otherwise leave it 'Default Image'. I would suggest setting "Link to profile" set to YES, so when someone is reading comments they can click the commentors avatar and be taken to their profile (Assuming you are using a third party component that supports profiles such as, Community Builder.
The last steps are completed by navigating to "Components>JComments>Settings>Permissions". Make sure 'Registered' and 'Super Administrator' (Administrator too if you have other admins), have "Show Gravatar" checked/enabled in the "Display Section."
I believe I have explained everything without missing any details, if you find any errors please contact me so i can fix this or if you have feedback or have suggestions please feel free to let me know.