It is surfaceparm, not surfaceparam.
A basic shader with texture and lightmap looks something like this:
textures/*/*
{
{
map $lightmap
rgbGen identity
}
{
map textures/*/*.jpg
blendFunc GL_DST_COLOR GL_ZERO
}
}
(replace the * with whatever needed) You can add the surfaceparm ladder in there, tho usually if you want to make a ladder, you'd just make a surface/model/whatever with the required texture, and then put a thin brush in front of or around it, covered with common/ladder, which makes that brush an invisible ladder.