The best known tradiion connected with leap years is that this is the one time when girls can decently make marriage proposals. Men are warned that it is bad luck to turn such an offer down, though - according to the Scots - they will be immune from such ill fortune if the girl concerned has neglected to wear a scarlet flannel petticoat, which must be partly visible, under her dress.
http://www.absoluteastronomy.com/topics/Leap_year
Feburary /29: Old Slavic Velja Noc/Great Night/New Year's Eve--Spirits of the dead visit their living relatives, overseen by Veles, Lord of the Dead.
People wearing animal masks and wool cloaks wandered through the villages representing the dead, and a grain effigy of the Morana of the old year was burned. Morana and Jarilo are born of Solntse (Goddess of the Sun) and Perun (God of the Sky). Veles steals Jarilo and raises him in Virey, realm of the dead. [a/k/a Wielkanoc]
http://www.en.wikipedia.org/wiki/veles_(god)
Powers greatly increased on this night. Invoke the spirits and the angels who might reveal the symbols and the secret words.