boot.wim driver integration

I'm trying to personalize a win 7 pro sp1 x64 for my laptop. It's a v3-571g:
Intel HM77 chipset
DEV_ID 1E03 (SATA controller)
DEV_ID 1E31 (Intel USB3.0 controller)
BIOS is set to Legacy mode
SATA controller is set to AHCI mode in the BIOS

Now... So far only the usb3 driver integration has worked:
1. sony usb3 stick boots up in the usb3 port
2. integrated usb3 driver works, I can get to the actual setup(else I get a window spamming "waiting for USB" or something similar as soon as the stick boots up)
3. I pick a language(i've integrated language packs)
4. after Setup is starting... I get the device driver prompt

I'm supposing at this stage setup is nagging for a SATA driver and that's just it - no matter what intel RST driver I integrate, it still can't see the SSD and HDD.
- I've tried the driver from acer's website, I've tried 11.1, 11.2 and 12.9 RST drivers from win-raid, original/modded drivers - still the same.
- I've tried integrating the drivers with dism /add-driver and NTLite - integration is successful, installation is not.
(I'm integrating the drivers into index 2 of the boot.wim; tried integrating into both - nothing)
- Even if I load the driver from another USB, it shows up in the Browse window, but it doesn't work.(also, I'm trying to avoid loading a driver from another device)

Just to be clear, it's not the end of the world for me if I don't get this to boot and install through usb3, I'm just very interested in accomplishing it.
So can anyone give me a hint what I'm doing wrong?

 

I've done the research and there's only the 1E03 sata controller, which is intel's. No third-party one. As far as I know, all the sata ports(2 in total) are from that sata controller. The SSD is where the HDD used to be. The HDD is where the optical drive used to be.

I've integrated a bg-BG language pack(boot.wim and install.wim), .net471/dx9 (MSMG) and I've simplix'd the install.wim(/ie11 /nousb /optimize).