This script takes your current object selection and automatically opens Adobe Photoshop and edits all of the Bitmap Textures assigned to that object.
I suggest assigning this to a keybinding CTRL-SHIFT-P to speed up your workflow.
1. Run script
2. In Max goto "Customize->Customize User Interface...->Keyboard tab->Category: ColinScripts->Photoshop Selected Material", click the "Hotkey" field and press CTRL-SHIFT-P. Press Save at the bottom.