Storage [Q] How to make Xperia S ROM to Acro S ROM? To have SD card support.

I have XPERIA Acro S, I know that Xperia S and Acro S has the same hardware and software, but the difference is Xperia S has no external SD card support. I'll gonna use Xperia S ROM like CM 11.0 by RaymanFX. My question is how to have SD card in storage (Settings>Storage)? How to edit the ROM to make it have a SD card support for Acro S? Please help and teach me what to do. Sorry for my English.

EDIT: > Xperia S, Acro S, Ion Q&A, Help & Troubleshooting
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Device: SONY XPERIA Acro S
Status: Unlocked Bootloader
Kernel: Stock .96 w/ CWM + TWRP +Init.d
ROM: Custom Jelly Bean ROM