General public is allowed from Abdul Hakeem to Khanewal section and vice versa but one has to be careful as you will face traffic coming opposite side and bikers/cyclist and pedestrians too. Getting onto this section is bit tricky. If you exited the m3 at Abdul Hakeem then you have to go Lahore entry point of m3 and from there take exit lane of m4 (not the Lahore entry lane) which is wrong principally but this is how people are managing.
If you are travelling from Multan to Khanewal section of m4, then when you pay toll at Shamkot toll plaza, ask them they will guide you how to get over motorway for Abdul Hakeem. It is simply a U-turn from that point.