Umm you can't with Bueno. It has a maximum image width in the post area of about 500px. Putting a 1024px wide image in there would mean more than half of it would be cut off.
Upload larger versions of the image and then link the smaller versions in the posts to those the larger versions which will open in the browser.
A couple things you should consider.
42% of those on the web are on 1024 x 768
17% of those on the web are on 1280 x 800
17% of those on the web are on 1280 x 1024
4% of those on the web are on 1680 x 1050
The above means that images wider than that will require a vast majority of people to scroll horizontally to see part of the image, and horizontal scrolling is the #3 out of 10 things people dislike on the web.
Also, a 1024 wide, or wider image is going to have a large file size. That means a slow loading page, and that is another thing people one the web detest. Also search engines are now using page loading times when calculating search engine placement and page rank. Slower loading sites with lots of images will take a substantial hit with the search engines.
My suggestion: Link the images in your posts and pages to the larger version and then if the person wants to wait for that huge image to download, they can.