sounds like you're plugging a texture in, textures "typically" go from 0-1 Specular power is a value that goes from 1-100+ usually. Either add and multiply the texture by scalar values, or use the specular power textures as the alpha of a lerp between 2 values.
I mean any mathmatical way you can create higher values than 0-1 will work. A lerp is the best solution because it's 1 instruction on the GFX card (Mult+Add). You can get more complex results by using fresnel to modify your specular power but a lerp is pretty much the bread and butter of mixing values.