The best solution for a game involving the 25mm or 28mm minitures I find is to go with 1"=2 meters. Now that you have that scale you can map out. Honestly I'd just divide the movement by 3 or the IP of the highest number of IP's in play should this become an issue. 9 times out of 10 though, this won't be an issue as the 1 IP guy is too busy dodging bullets to do much else (if they are smart).
Not that RAW is screwy in this regard ---as in the case of the 1IP human guy charging 25 meter to the 3 IP guy (troll street sam standing still). The 1 IP guy goes second (normally) and would get mowed down. On the off chance he spends edge or otherwise goes first he can run his full distance, engage in melee. But by raw on the second IP is not engaged in melee (IIRC) as the distance covered by the 1IP guy has only covered 2/3rds the distance (assuming he needed to run the full distance of 25 meters) and would get shout at and blown away.
OH..idea-moves involving a charge or engagement of the enemy result in the attacker delaying their attack until just before the targets last IP of the round unless they both have the same number of IPs-or the distance covered is equal to or less than attackers movement in terms of 1IP of the defenders. This works cause you divide the PC's or NPC's movement by the number of IP's they have.
Example 1:Ron the sec guard charges tammy the troll street same. Ron's charge move is 25m he has 1 IP< and spends edge to go first. Tammy has 3IP. Ron's charges the full 25 meters to tammy. Due to this house rule, Ron's attack is delayed until the 3IP. Tammy mows down Ron while he is at 8meters away on the first IP.
Example 2:Bob the sec guard charges tammy the troll street same. Bob's move is 25m he has 1 IP< and spends edge to go first. Tammy has 3IP.
Bobs only needs to cover 6 meter to get to Tammy. Due to the fact that 6 meters is less than 25(Bobs Speed)/3(Tammy's IP)=~8 meters, Bob's attack is not delayed and may immediately attack.
As you can see from the example here-while it is possible for it to become an issue, the scenario is a rare one indeed.