The Sam Adams website is very helpful as far as ingredients go. Pale and crystal malts along with Tettnanger, Hallertau Mittlefruh and "German Noble" hops are all listed. The beer is listed at 13 deg Plato (about OG 1.050). I think the blending of German hops has enabled SA to reduce its' dependence on the Hallertau Mittlefruh which was always highly touted in their old advertising but is very limited in production. The beer itself does not fit neatly into BJCP style categories but is in no way a Vienna other than having a similar color. Think of SA lager as a German pils with crystal malt.
8.5 lbs pale/pils malt
.75 lb Crystal 60L
SA does a decoction mash, try 131F for 20 minutes and 151F for 60 minutes. If you're not up for the decoction just go with the main rest.
1 oz Tettnager @ 60 minutes
1 oz Spalt @ 30 minutes
1 oz Hallertau Mittlefruh @ 10 minutes
Yeast suggestions are either the Wyeast 2035 or 2042.
This should get you pretty close to the color, ABV and basic flavor of SA.