This tutorials explains you, how to deal with the new spherify command, available since MilkShape 3D version 1.6.4. This command applies to all selected vertices. Generally, you can use this tool to blow things up or implode sections.
You can invoke this command from the menu "Vertex->Spherify...". You will be prompted for a value. You can enter values between -1.0 and 1.0. Note, that values higher than 1.0 can give some nice results too, so you might want to experiment a little.
Spherifying a box looks like following. Please notice, that I have subdivided 4 (Ctrl+4) the box two times, so that there are some vertices to spherify.
|before spherify||spherify 1.0|
|spherify 0.5||spherify -0.4||spherify 1.9|
Spherifying a Cylinder looks like following.
|before spherify||spherify 0.5|
|spherify -0.6 upper parts||spherify 0.6 lower parts||spherify 2|