TSP is exactly like a 401k and in fact is a 401k. Same rules apply. No need for a separate item in PL for it.

One way this is different from standard 401k’s is that TSP contributors have the ability to contribute Tax Exempt contributions into the Traditional TSP while deployed to combat zones. In that way, those contributions are able to be withdrawn tax-free; however, earnings attributed to them are taxable at withdrawal. That is referenced in the wikipedia reference that Aaron S. posted in the original suggestion.

For now you could handle this as close as possible by splitting your their TSP into multiple “accounts” in PL for each combination you have of regular vs combat excluded contributions, and Roth vs pre-tax. And then tweak the basis and taxation accordingly to get close enough.