Hello Gideon,
The toolchain is dependent on the kernel you are using on the BSP. In the case of the BSP releases the configuration is fixed to the kernel version and toolchain version listed on the release notes.
BSP release 3.10.53 does use the GCC 4.8.2 toolchain.
To get an older toolchain one option would be looking for an older BSP release that has the required toolchain. Another option would be using the Community BSP (although it does not include the Qt5 images) and configuring for an older kernel that is matched to the required toolchain.
I hope this helps!
Regards,