Hi Antonio,
no, there's no guide for such particular case. We provide only set of SDK examples and user manual:
c:\NXP\S32DS_Power_v2.1\S32DS\software\S32_SDK_S32PA_RTM_3.0.3\doc\S32SDK_MPC5748G_UserManual.pdf
Also notice that we provide only very limited support for lwip because it is open source. We can provide the support only if it is related to integration to SDK.
https://lwip.fandom.com/wiki/Further_lwIP_support
Regards,
Lukas