Not even sure if this is possible, but I want to be able to connect to a customers private network (they are using an RB952) into the private IP scheme the ISP uses just by changing the IP address in my computer. Is that possible? If so how? Thanks for any guidance.

Not enough info. It depends where exactly are you connected. Generally the answer is no. Private addresses are not unique. If your customer uses e.g. 192.168.88.0/24, the same subnet is used by another million of users all over the world. These addresses are not routable over internet. You'd either have to be connected somwhere very close (same ISP), or it should be possible to use VPN between you and customer's router. But again, you need to provide much more details, if you want any useful info.

From with in the ISP. From private customer networks inside the private ISP network. Nothing over the the public internet. Thru Mikrotik Routers. I want to go from the private side of the customers network thru the router to the ISP side just by changing the IP address of the laptop to a static one that is assigned by the ISP . The customers private network uses DHCP, the ISP uses static IP address's.