Ok, so basically what this does is enables you to get a pledge from an NPC that you didn't open the interact window with and also you can get a pledge from a male character while wearing cologne. It's quite useful for when there are two guards guarding a building or doorway and they are both the opposite sex.
Basically what you do is you open up the interact window with the NPC who you can get the pledge from (female if wearing cologne and male if wearing perfume). Don't give them the love token. Now target the guard/NPC standing next to them who you aren't wearing the fight perfume/cologne for and click the give love token option. The love heart will disappear from your targetted NPC and you will recieve the pledge but not from the NPC who you opened the interaction menu with.
This also works for targets that aren't standing next to each other and of the same sex. Basically it just gives the love token to your target as opposed to the NPC who you opened the menu with. Though I have found that if the target is really far away it won't always work but will work most of the time for targets up to 30-40 yards away.
Enjoy
EDIT: Because someone with 1 rep complains that it needed screenshots. You can tell that it's still the female's interaction menu because of her portrait on it.
[ame="http://www.youtube.com/watch?v=h5AFZAkUSIk"]YouTube - WoW Valentines pledges made easier[/ame]