Not able to populate email metadata in content server 10.5 using lapi

I don't think its possible with lapi and I would not certainly start any new development with lapi as it will be deprecated from CS16. I think currently the routine is only baked into Enterprise Connect module. In our scenario we were migrating lot of data(.msg files) and I had to write an OI extension that reads the msg properties using java libraries and then creates the llnode with the msg properties.