Script auto save png

Hi,
I need a script for resize and save a xcf file in png for the web. For go fast.
I've install this : http://registry.gimp.org/node/33#comment-14836
but i don't know how run the scrip. Who is it ? No info in README or INSTALL.

So, if you can write the script it for me. Thanks.

The procedure :

In GIMP :
Image>Image's size and scale :

SIZE :
-if L>H -> make L=800 pixels (and use chain)
-if H>L -> make H=800 pixels (and use chain)

RESOLUTION :
X=72 ppp (use chain)
Y=72 ppp (use chain)

QUALITY :

Interpolation : Cubic

clic in "Scale" for OK

File>Save As :

SAVE IMAGE :

path : default

name : if I want save "my_image.xcf" in .png use "my_image.png"

clic in "Save"

FILE EXPORTER :

tick : merge visible layers (default for me)

clic in "export"

SAVE IN PNG :

(my default profil) :
tick : Save resolution
tick : Save values ​​for the pixels transparent
Level of compression : 9
untick all ohther

clic in "Save"

END