You could cool the entire camera,
http://ghonis2.ho8.com/rebelmod450d16d.html
but unless you are doing this for the enjoyment of hot-rodding (cold-rodding?) the camera and the experience of it, I'd just do the filter removal, enjoy the camera as is for a little while, and then buy a 2nd hand cooled astro camera. You could get (for example) a QHY8 for about $900 without having to look too hard, and could sell your filter-removed 1000D to offset the cost. I did follow a guide at one point for cooling a DSLR, I'll see if I can find the link.