I have a Compact DCS that I am getting ready to add a 2-port StarMail.

Can station ports be used as SLT's? In other words, can I take my last two keystation ports and use them for the voicemail, or do I have to purchase a 2SLI card?

You will need the 2SLI card. Most cost effective.

That's fine, I'll locate one. By saying "most cost effective" implies that there is another solution. Curious as to what that is...

You can also add a 2x4SLI card, if you have an expansion cabinet and available slot. It will give you 2 Analog Lines and 4 Analog Stations.

Don't know exactly what you were refering to but what you just posted here was unnecessary.