+1 on Autohotkey.
Notice that each selection starts the wrong slot, then goes back to the in-game menu and starts the right one. So the script would do something like:
Start the right pack's executable
Wait for the program's window
Send Enter a couple times to choose the player/bankroll
Wait a couple seconds for the default (or last used) slot to come up (or look for a pixel, or unique window or whatever)
Send the Select Machine shortcut key from the right hand menu (on my old 2005 version, it was CTRL-L)
Wait a second for the game to bring up the list
Send 'Home' to get to the top of the list
Send the first letter of the chosen slot the right number of times. For example, Turkey Shoot was the fourth game that starts with T in that list, so send T four times.
Send Tab a couple of times to get over to 'Play'
Send Enter
Within the frontend, each of the blocks would run the script with the pack name and the letters that correspond to it, e.g. autohotkey startmasque.ahk texastea tttt for Turkey Shoot or autohotkey startmasque.ahk lobstermania ccc for Cleopatra