Split a complex LINESTRING & calculate distance

Hi

(using MS SQL 2008 R2)

Would it be possible to split a complex LINESTRING at a known intersection point on the linestring & then calculate distance on the half that contain the original starting point of the linestring.

Basically something similar to the "LocateAlongGeom" functionality in the CodePlex "sqlspatialtools" project, but slightly different that I know the point, but want to know the distance. (They know the distance and calculate the point)

 Much appreciated,

g