The linking variables are currently being tested by IPUMS-CPS and will become available by the end of the year, if not sooner. In the mean time it is possible to link consecutive March samples using variables available in the CPS files from NBER. You can merge the necessary information from the NBER samples onto IPUMS-CPS samples to link IPUMS-CPS files as well. See this answerfor more detail.
I hope this helps.