Substitute Mayas fcheck with AnimPlayer as the default image viewer:

• From the main menu select: Window > Settings/Preferences > Preferences
• At the bottom of the Categories section is the category "Applications"
• Under "Application Path for Viewing Images" enter the full path to AnimPlayer.exe.
  In the example it's AnimPlayers standard installation path:
  "C:\Program Files\AnimPlayer\AnimPlayer.exe"
• In the Optional Flags field enter: %f -singleframe

Substitute Mayas fcheck with AnimPlayer as the default sequence viewer:

• Under "Application Path for Viewing Sequences" enter the full path to AnimPlayer.exe.
  
• In the Optional Flags field enter: %f %s-%e %b

• To use AnimPlayer also as a Maya Playblast player you have choose AnimPlayer as Mayas default image viewer. Repeat the last two steps above for "Application Path for Viewing Images".
• From the main menu select: Window > Playblast and click the square options button at the right for the options dialog.
• In the 3rd row "View" make sure "Image Viewer" is checked.
• Checking "Remove Temporary Files" is recommended.