Ok. So there are a couple of solutions depending on whether you have SP Enterprise or not.
Enterprise: Use OneDrive for Business (Really nothing more than a SP Library, but hey... it's branded) just like you would for regular OneDrive.
Enterprise/Non-Enterprise: Load the file to a document library. Make sure you have permissions enabled on the file for everyone who needs to access it. Then point to it just like you would otherwise.
There are specific web parts for both access and excel. I would recommend building a sandbox and making sure the connections work from your SP environment to both before putting this on a production environment.
And honestly, in using the Access webpart, you can allow people to edit directly without even needing to interface Excel so long as you have the webpart and forms setup correctly.