This method is completely out of scope for 2D Toolkit, but some info nonetheless -
1. You'll need to draw the sprites as quads, using GL.Begin / GL.End, or as runtime meshes (using runtime sprite collections on the source textures) with a second camera, etc.
2. You have the source to tk2d, you can get the algorithms tk2d uses to pack these textures. tk2dAtlasBuilder.cs and friends.