What is the script Shrink Trimmed Srf? I can not find it anywhere
thank you

http://kyticka.webzdarma.cz/3d/moi/
See "List of commands without UI button"
-B

http://moi3d.com/3.0/docs/moi_command_reference10.htm#shrinktrimmedsrf

I have to create a shortcut to assign a keyboard key and enter the command ShrinkTrimmedSrf?

Yes !
Or Press Tab and write ShrinkTrimmedSrf
(you can write a little file text with some commands for copy/them after the Pressed TAB Key for reserve some ShortCut Keys for
another important functions or Plugins! ;)
More rustic but maybe more efficient than these more elaborate ones! ;)
You have also the Custom UI by Max Smirnov!
http://moi3d.com/forum/index.php?webtag=MOI&msg=6507.1

or list of Plugin / Commands by Marco
http://moi3d.com/forum/index.php?webtag=MOI&msg=7862.1

Thanks Frenchy Pilou (PILOU) :)