This is pretty useful, especially when you’re hacking your way around a new 4.2 installation, after having completely customized your old 3.x Movable Type.
How To Change the Default Image Upload Location in Movable Type 4.0
Since there isn’t an option within the Movable Type user interface to make the file upload utility remember that I want my images to always go into the images subdirectory I decided to go straight to the source and make it happen. Please remember that if these steps break your copy of Movable Type I’m not the least bit responsible.
Configuring the upload utility to upload to the same subdirectory by default is actually quite simple. It only requires editing a single line of a single .tmpl file. However, if monkeying with an application’s source code makes you really nervous I’ve heard there is a great plugin for improving Movable Type’s file upload utility that only costs $10.
The file to edit is called asset_upload.tmpl. Assuming you have your Movable Type files in your cgi-bin the path to this file looks something like cgi-bin/mt/tmpl/cms/dialog/asset_upload.tmpl.