Kludgy (marginally), but maybe further patch your Tk.pm and define something like $Tk::IS_FIXED_BOLEARY = 1 in it. Then you could prefix your call to cpanm with something like (adjusting for shell and how snippets need to be called in whatever you're doing):

perl -MTk -E 'exit( $Tk::IS_FIXED_BOLEARY == 1 ? 0 : 99 )' 2>&1 > /dev
+/null
if [[ $? -eq 0 ]] ; then
  echo "Locally patched Tk already present, skipping"
else
  echo "Locally patched Tk NOT present, installing with cpanm"
  cpanm https://BLAHBLAHBLAH/YACKETYSMACKETY
fi
[download]

Edit: Tweaked exit value check and tossed output. Derp.