Not sure if this will do it but App called File Shortcut does many things. Alternatively, Speed Dial Lite might also. If you want to pay VZW a subscription Visual Voice is a bloatware.
create a Contact called Voicemail. long press on a homescreen, choose Apps & Widgets, go to the Widgets section, and long press and drag the "Direct Dial 1x1" icon to the Homescreen. When you drop it, you will get the option to choose the contact. Choose the Voicemail Contact and you are finished.
To make it more convenient, I put two commas after the 611, and add my password, followed by #. that way I don't have to enter my password every time I dial voicemail.