1) Install PostGIS into your database if you haven't already
2) Copy the rtpostgis.dll to the lib folder of your PostgreSQL install
3) NOTE: If you are runing PostGIS 1.4 or below, you may need to replace 
Search for geometry_gist_joinsel in share\contrib\postgis\rtpostgis.sql\rtpostgis.sql, replace it with 
postgis_gist_joinsel
a) then Run the share\contrib\postgis\rtpostgis.sql in your postgis enabled db
b) You can install help now too by running share\contrib\postgis\wktraster_comments.sql
4) Copy gdal2wktraster.py to bin folder of your PostgreSQL install.
5) run the following query to verify you have wkt raster installed
SELECT postgis_raster_lib_build_date(), postgis_raster_lib_version();

-- Should give -- or a date later
 postgis_raster_lib_build_date | postgis_raster_lib_version
-------------------------------+----------------------------
 2010-03-31 23:00:00           | 0.1.6d

  
6) Run this quick example for creating a raster with code
CREATE TABLE rt_test (
    id numeric,
    name text,
    rast raster
);

INSERT INTO rt_test 
VALUES ( 0, '10x20, ip:0.5,0.5 scale:2,3 skew:0,0 srid:10 width:10 height:20',
(
'01' -- little endian (uint8 ndr)
|| 
'0000' -- version (uint16 0)
||
'0000' -- nBands (uint16 0)
||
'0000000000000040' -- scaleX (float64 2)
||
'0000000000000840' -- scaleY (float64 3)
||
'000000000000E03F' -- ipX (float64 0.5)
||
'000000000000E03F' -- ipY (float64 0.5)
||
'0000000000000000' -- skewX (float64 0)
||
'0000000000000000' -- skewY (float64 0)
||
'0A000000' -- SRID (int32 10)
||
'0A00' -- width (uint16 10)
||
'1400' -- height (uint16 20)
)::raster
);

SELECT name, ST_Width(rast), ST_Height(rast), ST_SRID(rast), ST_NumBands(rast)
FROM rt_test;

SELECT ST_Extent(rast)
FROM rt_test;

---------------------

Loading Raster data
To use the gdal2wktraster.py, you'll need python 2.5
You need to install Python first which you can get from below and install in 5 minutes or 
less:

Pre-compiled binaries are available here:
http://www.python.org/download/releases/2.5.4/


and Python GDAL bindings
http://trac.osgeo.org/gdal/wiki/GdalOgrInPython

If you don't want to fiddle with compiling your own, you can get pre-built 
binaries for GDAL for Python 2.5: 
http://pypi.python.org/pypi/GDAL/1.6.1
a) run the GDAL-1.6.1.win32-py2.5.exe


Note: There is a GDAL 1.7 egg, but no precompiled binaries for Windows so
tricky to get going.  Just stick with the 1.6 for now.

c:\python25\python gdal2wktraster.py --help 

c:\python25\python gdal2wktraster.py -r someimagefile -t sometablename -o somefile.sql
psql -U postgres -d postgisdb -h localhost -f somefile.sql

Details
on how to load raster data with the loader are found here:
http://trac.osgeo.org/postgis/wiki/WKTRaster/SpecificationWorking01

and here - this one is a bit dated:
http://mateusz.loskot.net/2009/03/30/crunching-wkt-rasters/

