Use WSI 
Code:
<AspDotNetStorefrontImport>
<Product Action="Update" ID="#">
<Variants>
<Variant Action="Update" ID="#">
<Dimensions>
<UOM>IN</UOM>
<Length>#</Length>
<Width>#</Width>
<Height>#</Height>
</Dimensions>
</Variant>
</Variants>
</Product>
<Product Action="Update" ID="#">
<Variants>
<Variant Action="Update" ID="#">
<Dimensions>
<UOM>IN</UOM>
<Length>#</Length>
<Width>#</Width>
<Height>#</Height>
</Dimensions>
</Variant>
</Variants>
</Product>
<Product Action="Update" ID="#">
<Variants>
<Variant Action="Update" ID="#">
<Dimensions>
<UOM>IN</UOM>
<Length>#</Length>
<Width>#</Width>
<Height>#</Height>
</Dimensions>
</Variant>
</Variants>
</Product>
</AspDotNetStorefrontImport>
<a href="http://www.aspdotnetstorefront.com">Shopping Cart Software</a>