Multiple scrolling textures in a shader

I'm using the following to scroll a texture in my shader:-

 void vert(inout appdata_full v)
 {
      v.texcoord.x = v.texcoord.x + _Time * _Speed;
 }

which gives me a scrolling texture in for my surf function. What I'd like to do is scroll two textures at different speeds. I'm not sure if this can be done in the vert function or if it's possible to do the scrolling in the surf function instead, where I have access to both textures.