This latest challenge was probably more interesting and fun that most of those we've had recently as it lends itself to many different paths to the solution.

I've discovered a few new techniques and tricks that surprised me, world weary old cynic that I am.

Anyhoo, here it is. Not the shortest, but a thing of chiaroscuric beauty none-the-less (in the authors humble opinion )

Code:
; begin Mayan Number Converter
;
;!
Function m($n)
	Dim $,$c
	If $n=Val($n)
		Do
			$=$n mod 20
			$n=$n/20
			Do
				$c=($>4)*3+IIf($>1,2,$)
				$=$-$c
				$m=SubStr("-.:xx|",$c+1,1)+$m
			Until $=0
			$m=" "+$m
		Until $n=0
	Else
		For Each $ in Split($n)
			$m=$m*20
			While $
				$m=$m+InStr(".:xx|",Left($,1))
				$=SubStr($,2)
			Loop
		Next
	EndIf
	$m=Trim($m)
EndFunction
;!
;!
; end Mayan Number Converter
; vim600:filetype=kix ai sw=4 ts=4