E-mail pathologists at programs, and ask for opportunities to do an observership. Even if they have nothing available they may know someone who does. It might help if you direct your e-mails toward people from your home country who are familiar with, or maybe even alumni of your medical school. Sometimes there are also professional associations of pathologists from particular countries who may be able to help.
Apart from a few programs that charge exorbitant fees for observership opportunities, I don't know whether programs have much to gain by taking observers. They do get the opportunity to evaluate an IMG's knowledge, communication and interpersonal skills in more depth than an interview would allow, which might be useful at programs that have trouble filling or have had bad IMG experiences in the past. Also quite a few IMGs were attendings in their own countries, sometimes in other specialties, so they have a lot of knowledge and experience that they can contribute for free.
But I think part of the reason someone might take an observer is just personal. Especially in path, many of the attendings themselves were IMGs who know how difficult the IMG experience can be. Those IMGs probably themselves received help from a US-certified physician and consider it part of their job to pay it forward. As a non-US IMG I managed to match and I know someday that when I am in a position to help a struggling IMG, I will.
It's not easy to find an observership, but it's far from impossible. Try hard and good luck.