How can I switch to Space 1 with the mouse? What can I do to be able to switch to space 1 easily with my mouse only ? I touch about an Exposé corner but there is a limited list of actions possible... I though about the 3rd mouse button but there is no space command in there...

Any idea ? Any trick ? 

EDIT : I see that on the 3rd button mouse, there is a "Other..." item in the popup action list. Choosing this opens a dialog where I have to choose an applescrit (as far as I know). Is it possible to make a script that switch to Space 1.

PS : I really want to shift to space one in 1-move or 1-click. I know how to go to Space 1 using only the mouse, But not "at once".
The mentioned BetterTouchTool can definitely do it via keyboard shortcuts.

After you install BTT, switch to Normal Mouse tab. There you click on + Add new mouse button and then click 3rd button inside the Click here to select mouse button.

Next, if you already haven't set up keyboard shortcuts to switch directly to a space, just pick any of the three modifier keys (CTRL, Option, Command), click inside the Custom Keyboard Shortcut field and press the key along with number 1, e.g Ctrl-1.



Note: if you have already set up such a shortcut, you have to disable it before trying to enter the shortcut to BTT, because OS X would otherwise capture this event and BTT won't get it.

Now close BTT window and go to System Preferences > Exposé &amp; Spaces > Spaces and select the appropriate modifier from the To switch directly to a space: list:



Now you should be able to switch to Space 1 directly with Middle click.

PS. I should mention that I have Magic Mouse and have BTT set up with three-finger gestures to switch spaces from mouse - very convenient.