CC: Importing past characters?

I'm just about to finish Chrono Cross my first time on New Game+. I keep reading about the ability to import characters from previous playthroughs provided you took a certain path to recruit some characters over others. I read that you have to go to the Dimensional Vortex which is accessed via The Hydra Marshes in Home World. I go there and look everywhere but I don't remember how to get back to the vortex!

I read some walkthroughs but they don't tell me exactly how to get back to the vortex. They simply say to go to the marshes in Home World and re-enter the dimensional vortex. That's all nice...but where is it?

Can any of you tell me how and where I can get back to the vortex (which screen is it on and any hints to where it is), what items to use, etc.? Thank you.:)

Finally: Once you get the Chrono Cross, go to Sprigg's house using the dimensional portal in Hydra Marshes (Home), one screen up from the start. Use the Chrono Cross and all your characters from your old game will join you! You can even get Harle this way, and you can use her to fight through Terra Tower. (I think that's a glitch, though. 8-))

Thanks for the tip, I managed to find it as you said. It was one screen north of the starting point in the Marshes where those two live "plants" are (the ones that either make a bridge for you to walk on or smack you - sorry forgot its name). I didn't know you had to search for the portal by pressing the "X" button and found it was just about below the tree trunk with the first "plant". I used the Astral Amulet as it mentioned with the portal appearing and I was back in Sprigg's home. Used the Chrono Cross and my previous characters from my first playthrough returned!

I finished the game finally and will probably not play the game for quite a long while - have lots others to go through;)