Make sure you are in edit-mode.

Highlight the texture area that you want to be scrolling
Press the console command key " ~ "
type
Code: Select all
/vscroll 1
and press enter.
you can also increase the speed ex:
Code: Select all
/vscroll 10
Code: Select all
/vscroll 20
Also if you want to change the direction type in
Code: Select all
/vscroll -1
Note: the player don't get effected by scrolling texture.