German forward Kneissl has yet to make an impact at Stamford Bridge since his arrival from Eintracht Frankfurt in the summer of 2000.
The 21-year-old trained with Swindon Town last autumn but failed to earn a move to the Second Division side. He has now been handed the chance of regular playing time with Dundee in The SPL where he will be reunited with former Chelsea coaches Jim Duffy and Graham Rix.
Midfielder Keenan has gone further afield in search of first-team football after joining Belgian club Westerlo.
Keenan has made three appearances for The Blues and will be aiming to use his spell in the Jupiler League to prove he is worthy of a chance in England.
Youth team attacker McKinlay has been loaned out to Ross County of the Scottish First Division.