Generally when sellers are open to selling their home via land contract, they discuss this with their listing agent. The listing agent then puts all the information about their property into a database that is searchable based on many different parameters, including search by purchase options (cash, conventional, land contract, etc...). Once this information is entered, other Realtors may pull that information to assist the listing agent in selling the property.
Unfortunately, selling a property via land contract is not a popular choice among many home owners. It may take some time to find the right land contract property for you.
So to answer your question, yes. Any Realtor within Southwest Michigan can help you locate a land contract home. I hope that this was helpful! Good luck!