The 50s wiring relates to how the tone capacitor is wired. Normally the cap is connected to the volume input lug (the same where the output wire from the switch goes to) and from there to the tone pot. Simply desolder the cap at the input lug of the volume pot and move it to the center lug of the volume pot. You're done.
What it does is twofold:
1) the tone pot and cap load the signal less when you turn down the volume pot, thus retaining more highs in your tone and
2) the tone control functions differently than before. When you turn down both the volume and the tone control you get a slight dip in the midrange which makes the tone actually brighter, again assisting in combatting mud.
Please keep in mind that 2) is a reason why some guitar players don't like 50s wiring. Try and see whether you like it.
As regards a treble bleed: this is either a cap and resistor in parallel or in series soldered between the input lug and center lug of the volume pot. For a 500kA pot I would suggest a 470k to 1M 1/4W resistor and a 150pf to 330pf cap (voltage rating is highly irrelevant here - the lower voltage caps are smaller in size).
Cheers Stephan