There is no complete package for now, so you will have to do it manually...
First, download files from these links :
1. "1812 Beta IV (v1.1) Full (Beta II, III & IV v1.1) (download the file below too !!)" -
http://www.sendspace.com/file/bmo3v1
2. "1812 Beta IV (v1.1) Textures (download the file above too !!)" -
http://www.sendspace.com/file/g6z4pw
Unpack file 1 and put the folder into ..../Mount&Blade Warband/Modules/(downloaded folder here).
Next, unpack file 2 and merge it with the aforementioned folder.
Hope this helps!