I suppose you will have to 'buy' from yourself with your CPF funds, since CDP is merely a depository in function. But then there will be still  be transaction costs.

In any case, maybe you can ask your broker if he can help you dispose of the odd lots. 

Odd lots and tradable odd lots are different. Singtel has tradable small 'odd lot' sizes for the convenience of many.

Any other counter can have odd lots resulting from consolidations, etc. eg. Hiap Hoe. Since these are  non-standard lots, they are more difficult to be traded, since the cost of doing so may make it not worthwhile..