Lex: I'm forcing a vote of the board of directors to accept an employee lead buy-out of the plant.

Lionel: What are you going to do? Convince the employees
to take out (make?) a second mortgage? Cash in (drain?) their IRA's.

Lex: Something like that.
I don't know about the UK, but in the US the term for entering into a mortgage contract with a bank is to "take out" a mortgage. "We had to take out a second mortgage on the house to pay for Dulcie's wedding, and then she got a divorce six months later."
"Cash in" means to liquidate. An IRA is an individual retirement [savings] account, which has certain restrictions attached to it along with tax advantages; there would be a financial penalty for "cashing in," or closing the account and taking its value in cash, before the individual reached retirement age.
Thanks, Delmobile!