http://www.mediafire.com/?er4eja1ao15lm63(Edit: also changed the link in this post to the correct one)
And there you go. It'll be a fair bit of work to integrate into your game since it isn't plug and play. You'll be better of using it as a reference and creating it from scratch in your own project so that you can choose which variables you need to set aside for it.
With regards to the demo project:
You can manually choose the "hero" sprite to display directly through the number keys 1, 2, 3 or 4 (Key Input Values: 11, 12, 13, 14). The numbers refer to the slot in the party.
You can cycle through the party members with the Shift Key (Key Input Value: 7).
If necessary, you can change the Key Input Processing values should you make use of them already.
When you remove party members, variables will be updated accordingly. Should you remove the last party member it's pretty straightforward. If you remove the party member in the 2nd slot, then the necessary variables are updated to "move down" the party members. Thus the variables holding the IDs of the heros in Slot 3 and Slot 4 will be moved to Slot 2 and Slot 3 respectively, allowing for seamless transition when you begin to cycle/choose graphics again.
Also, if you remove the lead actor - the actual hero in party slot 1 - everything will be updated properly. The slots will be moved down as above, and the correct graphic for the new lead actor - the actor who was in slot 2 - will be shown instead.
In all, it's pretty seamless (at least in my initial testing).
In terms of what you will need to find space for:
5 Common Events
11 Variables
Aside from 2 instances (adding and removing heroes) everything is handled with Common Events; 1 which is Parallel, the rest are called. The most commonly called CEs will be the ones to add and remove heroes. Because these CEs handle actually adding and removing party members, you'll need to make edits to any other systems that add/remove party members to allow for correct compatibility - certain variables need to be updated when adding and removing heroes, thus why the CEs will handle this process.
You can check the events on the game map on how adding/removing is done - basically, a variable is set that contains the value of the ID of the party member to add/remove and then you call the respective CE. Within that CE you interpret that ID to add/remove the appropriate party member. At the same time, all of the necessary variables are assigned the appropriate values that allow the graphic changing to work properly. It shouldn't be too difficult to make a few edits to your PHS system to work.
Once you've gone through setting up and expanding the CEs that are used, there's very little extra work (aside from compatibility fixing).
It's pretty well commented, but if you have any questions about how it works or how to set it up, just let me know.
All in all, I'm pretty pleased with it. It made a change to go back to 2k3 and make an evented system. I used to do a fair bit of work with events, even did a few tutorials. With the more recent RMs involving scripts it's quite easy to forget that making an evented system can be pretty fun, and not really that hard either.