If you are not seeing code "106" (long-term premiums) as a selection in the Virginia program, it is likely because first the long-term premiums must be entered in the Federal program, under Itemized Deductions (not to be calculated and taken on the Federal return, only to let code "106" appear on the Virginia return). Once that information is entered, you will see the code as a selection on the Virginia return.
To enter the long-term premiums:
You would then also ignore the Yellow Alert "Warning: Insurance Premiums" when you run the Alerts which tells you to enter the age of the person for the Federal entry, because you do not want the deduction to be taken on the Federal Schedule A (Form 1040) Itemized Deductions.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.