I haven't finished exploring the encoding mechanism, but here's a basic summary.

Each group of 3 characters is used in the creation of one output character. The character code is generated by summing the following:

chr(
 5 * (
   5 * l($char1)
   +l($char2)
 ) 
 + l($char3)
 + 2
)
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Where 'l' is a subroutine that does:

int ( ord($char) - 42) / 16
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Here is the translation for the first 11 sets:

[::j] chr(2+5*(5*l(:)+l(:))+l(j)) = chr(5*(5*1+1)+4+2) = $
[jJj] chr(2+5*(5*l(j)+l(J))+l(j)) = chr(5*(5*4+2)+4+2) = t
[J:r] chr(2+5*(5*l(J)+l(:))+l(r)) = chr(5*(5*2+1)+4+2) = =
[BBR] chr(2+5*(5*l(B)+l(B))+l(R)) = chr(5*(5*1+1)+2+2) = "
[scC] chr(2+5*(5*l(s)+l(c))+l(C)) = chr(5*(5*4+3)+1+2) = v
[C[k] chr(2+5*(5*l(C)+l([))+l(k)) = chr(5*(5*1+3)+4+2) = .
[kKj] chr(2+5*(5*l(k)+l(K))+l(j)) = chr(5*(5*4+2)+4+2) = t
[j:J] chr(2+5*(5*l(j)+l(:))+l(J)) = chr(5*(5*4+1)+2+2) = m
[jJ*] chr(2+5*(5*l(j)+l(J))+l(*)) = chr(5*(5*4+2)+0+2) = p
[>>N] chr(2+5*(5*l(>)+l(>))+l(N)) = chr(5*(5*1+1)+2+2) = "
[N>N] chr(2+5*(5*l(N)+l(>))+l(N)) = chr(5*(5*2+1)+2+2) = ;
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Which yields:

$t = "v.tmp";
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This encoding gives a great deal of flexibility in the characters used, as every column is divided by 16 before it is touched by the decoder.

The resulting perl script is as follows:

 $t="v.tmp";open($f,">$t");
print $f "
let L=[\"[][+/13579;=?_acegikmoqsuwy-]\",\"[],014589<=@%`adehilmpqtuxy
+-]\",\"[/.016-9>?@^_`af-in-qv-y]\",\"[2-9b-ir-y]\",\"John C. Norton '
+liverpole'\"]
let v=8
let C=255
let W=C
let x=3
se hls ic
wh 1
let C+=v
if C>254
let v=-v
let C=255
let x=(x+1)%4
let y=L[x]
let f=1
elsei C<1
let C=0
let v=-v
en
go 1
let R=x%2?W :C
let G=x==2?W :C
let B=C
if !x || x>2
let B=W
en
exe printf(\"hi Search guibg=#%02x%02x%02x\",R,G,B)
exe \"/\".y
redr
if f
sl
let f=0
en
sl 100m
endw
";close$f;
system("gvim -c \"so $t\" \"$0\"")
#jcn
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Which basically writes a temp file containining vimscript, then opens the perl script in vim, and sources the newly created vimscript - which is as follows (with variables renamed and indentation added to make it easier to follow):

let search_patterns=["[][+/13579;=?_acegikmoqsuwy-]","[],014589<=@%`ad
+ehilmpqtuxy-]","[/.016-9>?@^_`af-in-qv-y]","[2-9b-ir-y]","John C. Nor
+ton 'liverpole'"]
let vector=8
let C=255
let n_pattern=3
set hlsearch ignorecase
while 1
  let C+=vector
  if C > 254
    let vector = -vector
    let C=255
    let n_pattern=(n_pattern+1)%4
    let pattern = search_patterns[n_pattern]
    exe "/".pattern
    let f=1
  elsei C<1
    let C=0
    let vector=-vector
  end
  goto 1
  let red = n_pattern % 2 ? 255 : C
  let green = n_pattern == 2 ? 255 : C
  let blue = C
  if !n_pattern || n_pattern > 2
    let blue = 255
  end
  exe printf("hi Search guibg=#%02x%02x%02x",red,green,blue)
  redraw
  if f
    sleep
    let f=0
  end
  sleep 100m
endwhile
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