I've seen recipes for maple sap, but never maple syrup. I think the syrup might be too concentrated with sugar, that's why I haven't seen a recipe.
However, I just find this recipe on scorpius:
12 gallons maple sap, reduced to 1 gallon
2 oranges or 1 lemon, sliced thin
1 campden tablet
1 package wine yeast
Place maple sap in primary fermentor. Add water and sugar, if using. Add oranges or lemon and campden tablets. Let sit overnight.
Next day, Specific Gravity should be 1.090 - 1.100. Stir in yeast. Stir daily for 5 to 6 days or until Specific Gravity is 1.040. Strain out fruit and squeeze as much juice out of it as you can. Siphon into secondary fermentor and add airlock.
For a dry wine, rack in three weeks, and every three months for one year. Bottle.
For a sweet wine, rack at three weeks. Add 1/2 cup sugar or maple syrup dissolved in 1 cup wine. Stir gently, and place back into secondary fermentor. Repeat process every six weeks until fermentation does not restart with the addition of sugar. Rack every three months until one year old. Bottle.
The wine is best if you can refrain from drinking it for one full year from the date it was started.
Now, I'm thinking that 12 gallons of sap boiled down to one gallon would equal 1 gallon maple syrup. I'd check the SG of your syrup first, to ensure that it is in the 1.090 range or so. Then either add more sugar, or use less syrup to get you in the 1.090-1.100 range.
Good luck, and let us know how it turns out!