Tcl 8.0.5, 344 (360 bytes)
set a ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789
set s string
set x [join [lsort [split [$s toupper ABC321STPpJqZZr0] ""]] ""]
regsub -all (.)\\1+ $x \\1 x
set i 36
while {[incr i -1]} {set j -1
while {$i+[incr j]<36} {set y [$s range $a $j [expr $i+$j]]
regsub $y $x [$s index $y 0]-[$s index $y end],\ x}}
while {[regsub -all {(\w)(\w)} $x {\1, \2} x]} {}
puts $x