What are the mechanics and inputs in Lacerte for this situation? 

The TP got no UI while the Spouse got 27K UI

The result should be 6,600 of taxable UI  (27,000 - 20,400)

I'm fairly certain that screen 14.2 is the form for the input. Should I use two input lines - one for TP and one for Spouse and allocate 13,500 of UI to each?

Spidell - a supplier of tax education in California advised this:

If a married couple's combined AGI (calculated without any UI compensation) is below $150,000, then MFJ taxpayers may exclude up to $20,400 of unemployment income even if one of the spouses had less than $10,200 in UI and the other spouse had more than $10,200. That is because California is a community property state and the Tax Court has recognized that UI is treated as community property. (Calhoun v. Commissioner (1992) 64 TC 222) However, your tax software may not properly split this income, and could improperly limit the exclusion if one spouse received less than $10,200. Tax professionals need to watch out for this and apply a manual override in this situation.