No, there will never be a version which does not require the .net framework. That would be a completely different application, written from scratch. Even the boo scripts require the .net framework, so any application compatible with them would also require it.
To download covers using the command line, use the aad.exe command line tool. I'm sorry the wiki pages aren't working at the moment, but the command line reference can be obtained locally by using the parameter /?.
At its most basic, aad.exe "artist" "album" Folder.jpg will search all available sources for the specified artist and album, and save the result as Folder.jpg in the current folder.
For convenience, here is the full aad.exe command line reference:
Usage: aad.exe [options]
Option names may be preceded by a / or a -
Options:
/artist Artist to search for (/artist "Artist Name")
May be abbreviated to /ar (/ar "Artist Name")
Parameter name may be omitted
if this is the first parameter ("Artist Name")
/album Album to search for (/album "Album Name")
May be abbreviated to /al (/al "Album Name")
Parameter name may be omitted
if this is the second parameter ("Artist Name" "Album Name")
/path Default path to save art as (/path "\Art\Folder.jpg")
May be abbreviated to /p (/p "\Art\Folder.jpg")
Parameter name may be omitted
if this is the third parameter
The following variables can be used in paths:
%artist% Artist searched for
%album% Album searched for
%name% Name of the image found
%extension% Default file extension for the image
%source% Name of the source where image was found
%size% Dimensions of the image
%sequence% A sequence number for the image, corresponding to
the number passed to /sequence, or "1" by default
/sources Specifies the sources to search, (/sources "Amazon,Coveralia")
in the order to search them.
Separate sources with commas.
If omitted, all available sources
except those excluded by the /exclude
option are searched.
May be abbreviated to /s (/s "Amazon,Coveralia")
/exclude Does not search the specified (/exclude "Local Files,Google")
sources. Separate sources with
commas.
May be abbreviated to /es (/es "Local Files,Google")
/minSize Specifies the minimum size of (/minSize 300)
image, in pixels, to use.
Both horizontal and vertical
dimensions must conform.
May be abbreviated to /mn (/mn 300)
/maxSize Specifies the maximum size of (/maxSize 1000)
image, in pixels, to use.
The smallest dimension of the
image must conform.
May be abbreviated to /mx (/mx 1000)
/minAspect Specifies the minimum aspect ratio (/minAspect 0.9)
of the image to use. This is how
square the image must be, where a
value of 1 represents perfectly
square (600 x 600, for example). An
image of size 600 x 300 would only
be allowed if /minAspect were 0.5
or lower.
May be abbreviated to /ma (/ma 0.9)
/sequence Specifies which result to use, if (/sequence 2)
more than one are found. For
example, passing 2 as the value
here would ignore the first result
found, and use the second.
May be abbreviated to /seq (/seq 2)
/listSources Produces a list of all available (/listSources)
sources to search.
May be abbreviated to /l (/l)
Exit errorlevel codes:
0 Success
1 No image found
-1 Error occured