Does a breastfed infant gain immunoprotection due to intramuscular vaccination of the breastfeeder?
Vaccinating the mother or a breastfeeder to provide immunization for the baby through breastfeeding is not proven nor recommended by health authorities. 

If a mother is vaccinated intramuscularly or any other route, it will anyway pass IgA and IgM, and to a much lesser extent IgG antibodies to the baby through breastmilk but it is not proven to confer specific immunity against all pathogens.

And as per your other question, a child from a mother who hasn't had any infection/vaccination with Hepatitis A and hasn't passed any IgG through the placenta will not be conferred immunity against Hepatitis A even if it is breastfed from a woman who had the infection or was vaccinated against Hepatitis A. 

There are other ways a mother's breastmilk can induce immunity (cell immunity) this is currently under research and it has been proven to confer immunity in animal models in recent studies but is still not a medical recommendation in humans (studies in pups regarding passing immunity through foster breastmilk for candida albicans , tuberculosis and helminth infections). 

What is already proven is that breasfeeding and vaccination of the baby does provide with a more robust vaccination response so that is why breastfeeding and vaccination to the baby at the same time are encouraged. 

Maternal Milk T Cells Drive Development of Transgenerational Th1 Immunity in Offspring Thymus

Pre-conception maternal helminth infection transfers via nursing long-lasting cellular immunity against helminths to offspring