My client is wanting to roll his 401K into a Roth 401K because they have little income now.  

I am confused as to what forms and where it should be entered.

It appears I need to take the 13.1 Pension and IRA and enter the distribution and such but in the Rollover section it only talks about rolling into a Roth IRA not a 401K.  I want to make sure that is okay to use or is there a hidden 401K Roth Rollover box somewhere?

Thanks.