Dear Saddian,
No, the Sedna O11DXL only can be mounted on the front side of the Lian li O11D XL. Or you can choose the BPTA-WDPO11DTE-K1M or BPTA-WDPO11DE-PWM-V2 on the side mount.
https://shop.bitspower.com/index.php?route=product/search&search=O11DE