Not really, as this manoeuvre would have no effect on them. In the same way, when a fleeing skirmishing unit rallies, there is no need to do anything other than turning its models on the spot so that they face towards the enemy!

In the Move Chargers part of the Movement phase, the player controlling the chargers must decide which unit goes in first against the skirmishers and move it in. The skirmishers are then immediately formed up normally against the first charger. At this point the skirmishers have a front/flank/rear zone, and any other charging enemy must treats the situation just like a charge against a fight that was there from a previous turn.

It seems fair that, in this most rare of circumstances, you are still allowed to charge the skirmishing unit by contacting the nearest visible skirmisher you can reach.

If the skirmishers are fleeing from a combat the situation is easy, as they are treated exactly as a normal ranked up unit. If they aren't, the situation may get a bit more complicated. First, the closest visible skirmisher flees directly away from the centre of the charging unit by the distance rolled. Then, every other fleeing skirmisher is moved by the same distance along the same (parallel) direction as the first, trying to keep the skirmishing unit as much as possible in the same formation, as shown in the diagram below.

Salamanders are not Monsters (their special rules say they have to take Monster reaction tests, but this, like all special rules, is an exception). So Salamander Packs are simply a skirmishing infantry unit. Monsters, by definition, are single large models (like the Hydra).

The rules are clear on the matter – the Monster & Handlers move as Skirmishers so can move freely through difficult terrain, but when charging are slowed as normal.