Hi Pilou.
"because I have written QuickSplit_XYZ X (y or Z) and nothing work !!! :)"
Good point! :) I should have been more clear -- it's:
QuickSplit_XYZ X
QuickSplit_XYZ Y
QuickSplit_XYZ Z

For the Angle script there is no parameter to enter. The angle is chosen by where you place your 2 points on the model.

Paul

PS --
After playing around with QuickSplit_Angle for awhile I realized Pilou was thinking "angle as defined by a specified angle". Turns out there is a way to do that with this script:
Pick your object, hit your hotkey, pick the location you want the split to run thru, go to the angle box at the bottom of the gui and enter a number for the amount of precision you need for the angle, that turns on snapping set to that precision. Then pick your 2nd point on the model, after moving the pointer around until you get the angle you want. The split will be done at the specified angle. In other words, if you want a split at 45 degrees, enter 5 in the angle box and snapping will happen at increments of 5 degrees. If you want 22.5 degrees, type in 0.5, snapping sets to 0.5 degree increments.
The more I use MoI, the more I realize how well thought out Michael's design is!