Here is some github code to create split keys.
Is Key Splitting the same as Multi Sig?
What are the benefits of Key Splitting, what's it used for?
How does it relate to P2SH or any other relevant BIP?
How are split keys used in a transaction?
The major problem with split-key transactions is that you need a trusted third party. When they generate the key, they could secretly store it. When they put the key back together, they could secretly sign a transaction that stole all of your bitcoins.