Hi Phoenix. I was intrigued by your post - we don't see Peruvian beers being discussed much. I Googled Cusqueña Malta and it appears that it's marketed as a schwarzbier. However, reviews seem to note that it's too sweet/malty to be true to style. See ratebeer.com and also this page:
http://www.epinions.com/content_4358774916It doesn't help that you've only got a second hand description to go by. If you're having trouble finding a bottle, maybe get your friend to try something more readily available like a domestic schwarzbier like Duckstein's, and see if she thinks it's close, then work a recipe out based on what you taste in that. I couldn't find anything on Scarlett malt. According to probrewer.com, Metcalfe malt is a Candian 2-row that's ideal for lagers, so any pilsner or pale lager malt would probably do the job as the base malt. Without knowing more about the beer you're trying to clone, you could start at 50% pale, then fill in the rest with Munich I or II and some chocolate malt (4-8% - you can end up with more coffee flavour than chocolate though), some crystal or Caramunich for extra sweetness and colour, and small amounts of carafa for colour.
For a partial, I'd start with pale extract or a tin of something bland and low IBU like Cooper's lager instead of pale base malt, then mash as much of the rest as possible. If you can't mash that much, you could add liquid Munich extract (or amber if you can't get it). Take the kit IBUs into account, and chuck in some Saaz, but no later than 25 mins in the boil, as I'd imagine that this beer has little to no hop character. The BJCP specifies the IBU range as 25-35, so keep it towards the low end of that if your friend likes a sweet beer.
Pitch a massive starter of a lager yeast that accentuates the malt profile (read the yeast descriptions for an idea of which one to go for). You might be able to get away with fermenting at the warmer end of the yeast's recommended range as you're going for a malt-driven beer. Condition as close to freezing as possible for as long as possible.
Good luck!
EDIT: changed the recipe advice slightly