RPG MC should walk more exactly

have want to do a flash rpg and so i have tried a lot of thinks
i wanted to do for every map an own image but then i recognized that the traffic would be very bad -.-

then i found this site and the cool tutorial for doing dynamic maps ^^

but now i have a problem with my rpg mc and i haven’t found anything here

The hittest is working well but i think it’s still not perfect.
This is a test site:

I want that my mc walks more exactly, so he would go nearer the river

How can I set up the hittest that it only considers the “shadow” (the feet) of my mc ???

Please help me

PS: my sorry that my english is so bad -.- it’s not my native language but it can understand it very well but I have problems with writing