reproject shapefile?

I have a feature service published in WGS 1984 Web Mercator Auxiliary Sphere: 

WGS_1984_Web_Mercator_Auxiliary_Sphere

 

WKID: 3857 Authority: EPSG

Projection: Mercator_Auxiliary_Sphere

 

False_Easting: 0.0

 

False_Northing: 0.0

 

Central_Meridian: 0.0

 

Standard_Parallel_1: 0.0

 

Auxiliary_Sphere_Type: 0.0

 

Linear Unit: Meter (1.0)

Geographic Coordinate System: GCS_WGS_1984

 

Angular Unit: Degree (0.0174532925199433)

 

Prime Meridian: Greenwich (0.0)

 

Datum: D_WGS_1984

 

  Spheroid: WGS_1984

 

    Semimajor Axis: 6378137.0

 

    Semiminor Axis: 6356752.314245179

 

    Inverse Flattening: 298.257223563

Using my Silverlight Viewer, I need to be able to select individual features from this service and export shapefiles to a custom Mississippi Transverse Mercator projection:

MSTM

 

Authority: Custom

Projection: Transverse_Mercator

 

False_Easting: 500000.0

 

False_Northing: 1300000.0

 

Central_Meridian: -89.75

 

Scale_Factor: 0.9998335

 

Latitude_Of_Origin: 32.5

 

Linear Unit: Meter (1.0)

Geographic Coordinate System: GCS_North_American_1983

 

Angular Unit: Degree (0.0174532925199433)

 

Prime Meridian: Greenwich (0.0)

 

Datum: D_North_American_1983

 

  Spheroid: GRS_1980

 

    Semimajor Axis: 6378137.0

 

    Semiminor Axis: 6356752.314140356

 

    Inverse Flattening: 298.257222101

Is there a way to reproject features for export from silverlight?