LM350 as current supply with Li-ion batteries
You could adapt a circuit like this which uses a linear regulator, this gives an example of how to use a linear regulator to do a constant current.


Source: http://www.tij.co.jp/product/jp/LM3420/datasheet/application_and_implementation#SNVS1168511

The one problem with this is you need constant current, then constant voltage, and the circuit above at first glance does not appear to be able to do the constant voltage part.


Source: http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries

You are better off (and probably cheaper) to buy an charge controller in an IC or on a proto board