Yay, 3.9+ has Custom Song/Profile Mem Card Support! But the only problem is that if you only plug in one card, it will automatically go to Player 1. Therefore, to get a card in the Player 2 slot, you have to plug in two cards and plug in P2's card second. Here's how to fix that problem:
1)Download USBDLM Here:
USB drive letter manager - USBDLM
2)Unzip it to C:/Program Files
3)Open up the Program Folder and click the file named "_install"
4)Now you have to find out what your USB port names are. Plug a flash drive or other USB device into one USB port, then click on "ListUsbDevices" in the program folder. In the window, go to the line that says "USB Port Name = #-#" and that is your USB port number. Do this for the other USB port, too.
5)Go into USBDLM.ini and type these lines:
Code:
[DriveLetters1]
PortName=1-5
Letter=Y
[DriveLetters2]
PortName=1-6
Letter=Z
Of course, you would replace my USB port numbers (1-5 and 1-6) with your numbers. And you don't have to use Y and Z, you can use any two letters. Save the ini file.
6)Now, go into the SM program folder and go into the Stepmania.ini. Find these lines and fill in your drive letters:
Code:
MemoryCardOsMountPointP1=Y:/
MemoryCardOsMountPointP2=Z:/
I used Y and Z, you don't have to. Save the ini.
And now you're set! Now when you plug a flash drive into one USB port, it will be P1, and when you plug it into the other, it will be P2! No matter who inserts theirs first or second!
I made this guide mainly for people who play SM on the 2P side, and the memory card kept going to the P1 slot.
If you don't get what I did or I didn't explain enough, ask your questions and I'll be glad to help.
(SM 3.9+) How to assign different drive letters to USB ports 
