Your idea is flawed on several levels, and i honestly cannot recommend you try to do this. The biggest reason plain and simple is that a compound system normally works with a positive displacement supercharger, of which there are none for the 3.7L, and a rather large turbo. The Positive displacement supercharger essentially looks to eliminate the lag of the larger turbo, and the larger turbo increases the efficiency of the supercharger by force feeding it. The two offset the weakness of the other.
The only supercharger available for the 3.7L is a centrifugal supercharger, which does not build large amounts of low end torque like a positive displacement blower. So basically trying to compound this with a turbo you would end up with massive amounts of lag from the nature of the centrifugal supercharger compounded with a large turbo, or by running a small enough turbo to negate any lag you would be incredibly limited on the exhaust side of this set up to warrant the time, money, and effort that has gone into it.