How to set up some M-48 mixes on a computer with the S-4000RCS?

How to save these different mixes and then somehow copy these mixes onto actual M-48 units once I get on-site?

In your offline PC, create M-48 Mix #1 on the Virtual M-48.

Then, click the big MENU button in upper center of the M-48 Manager window and click "Library". Highlight Library 01 Slot, then click "Store". You can name this Library Slot whatever you like. Then, use the Virtual M-48 to create Mix #2.

Save the new settings in the Library as Library Slot #2. Repeat as necessary.

When done, close the M-48 Manager and in the S4000RCS main menu select FILE > SAVE AS. Name it and save it. Copy or open that saved xxxx.S4R file on the PC at the facility.

Open that PC's S4000RCS and select File > Open, then browse to your S4R file and open it. Use the Port drop-down to connect to your REAC device and all the M-48's Go to the M-48 Manager. Open the Library and Recall Library Slot #1. The Virtual M-48 will adopt those settings. Then, select which actual M-48 you want to have these settings and click the MEMORY button and STORE the settings to one of the MEMORY slots in that M-48.

Now, whenever you or the talent Recall that M-48 Memory Slot, you will get the settings you made in that Library Slot. In short, a Virtual M-48 Library Slot becomes a Memory Slot on the actual M-48. And all your Virtual M-48 Library Slots are kept in the S4R file.

This should do what you are hoping to do.