Insert M6 bolt from the front. Now turn the whole thing over, placing on a hard surface (eg workbench) so that the M6 bolt is resting on the workbench.
Now tap in a Torx wrench bit (gently). Because you have the M6 bolt on the other side, this won't drive the bolt any further into the fork.
Once the Torx bit is in place, unscrew gently whilst pushing the fork gently downwards, so that your M6 bolt helps push the nut out.
Insert M6 bolt from the front. Now turn the whole thing over, placing on a hard surface (eg workbench) so that the M6 bolt is resting on the workbench.
Now tap in a Torx wrench bit (gently). Because you have the M6 bolt on the other side, this won't drive the bolt any further into the fork.
Once the Torx bit is in place, unscrew gently whilst pushing the fork gently downwards, so that your M6 bolt helps push the nut out.