Just run the setup file you downloaded and follow the 
instructions given to install it. The program will run
 in your system tray. To assign hotkeys to raise and 
lower the volume, do the following. First press insert f11
 for the system tray dialog. Arrow to where you will find 
"volume % Volume Control Master Levels" and press enter. 
This will bring up a context menu, choose open volume 
control and hit enter. This again brings up another context menu.
So, arrow down to open volume control and press enter. 
Then hit control P to bring up the preferences dialogue. 
Then control tab once to the hotkeys tab. Then tab three 
times to where you can then use your up and down arrow keys
to see the list of items for which you can make hotkeys. 
Here you assign keys for volume control, such as raising 
and lowering the volume. The first one is for volume up. 
If you wanted to assign the hot key control shift up arrow,
then check checkbox for hot key enabled, check the checkboxes
 for control and shift, and uncheck the checkbox for alt.  
Leave the word up in the edit field. The next checkboxes will
 be for volume down. In the same way, to assign control shift down arrow, check the box for enable hot key, check the checkboxes
 for control and shift, uncheck the checkbox for alt, and leave
 the word down in the edit field. Tab to apply hot key changes 
and enter. Tab to hide and press enter to return volume tray to the system tray. Try your new hot keys of control shift up and down
arrow to raise and lower the volume. 

Note: Please be careful in the keystrokes you choose, as they
 might be used by another program.  For example, the above 
keystrokes are used in Word for selecting text and so would not
 be a good choice for you if you use Word as volume tray would intercept them.