Photoshop uses the spacebar as the modifier to zoom and pan images. Photoshop has the following ways to pan across your images:
“H” selects the Hand tool.
Holding down the spacebar (while most other tools are selected) will temporarily access the Hand tool (allowing quick panning of images that are zoomed in). This shortcut also works while in a modal state (such as while a dialog box is displayed or while in Free Transform).
When using the Hand tool to pan, Photoshop “eases out” of the pan (this is referred to as Flick Panning). For an abrupt stop when panning, click, drag and hold with the Hand tool. Note: Flick Panning can be disabled in Preferences > Tools > Enable Flick Panning.
When viewing multiple images simultaneously, Shift -drag with the Hand tool to pan all open documents. To set this as the default behavior, with the Hand tool selected, check “Pan all Windows” in the Option bar.
What can you not do? I have no problem assigning H to the middle mouse button. I can hold it press the add the left click to get Spring H Zoom out position the area box let go of the left mouse button zoom back in then let the middle button up to switch back to the original tool. Or I just tap the middle button to switch to the hand tool the pan with the left mouse button. When the hand tool is the current tool I can also press and hold the middle button then add the left mouse button to get the Zoom out and position the area box let the buttons go to zoom back in.
What my original post says. I don't want to do all the crap you are talking about, I want to assign panning to middle mouse button. I don't want to change my middle mouse button in third party software just for adobe photoshop... that is not a solution.
You wrote that was suggested or requested of Adobe 9 years ago. So maybe some day Adobe may consider it or perhaps they rejected the idea or request. Adobe does not make public all their plains.
You should do something for what you want to do is not currently possible with Photoshop and may never be possible. I like a $1,000,000.00 but realize its not in my cards. So I make do with What I have I can pan with my fingers..