this is all very plausible... i have been underneath the crossfire figuring out my plumbing to the remote mount turbo a few times in the past few days... all is going well so far except i have a small issue with running two sets of 2 inch pipe back to the front... one is for the pressurized side that will feed into the supercharger from the turbo, the other is for the air filter that will feed the turbo...
i simply cannot do a system like STS where they leave the air filter underneath the car in the back; one good puddle and the motor is a hydrolocked brick...
you will need additional fuel to do this and the options for this are:

reprogrammed ECU - high cost, very few places can do this, messing with factory equipment means no turning back, and no tunability unless you pay the shop to do the reprogramming again
mechanical fuel pressure regulator/return line system - arcane at best.. getting the proper fuel curve is a luck shoot
secondary fuel injector - my choice for the past six years, add a secondary fuel injector on the pressurized pipe coming out of the turbo. the fully atomized fuel mixes completely with the air charge and distributes equally across all cylinders (so long as intake manifold design is not crap). only issue with this, for twin charging, i would not want fuel rich air going through the supercharger to be pressurized further, umm kaboom. BUT you can always do as i did with my previous vehicles and cram in a secondary injector next to the OEM injector... easier said than done on the SRT-6 since things are rather tight in that area already ! surely a feat you would rather have a custom CNC shop handle along with custom machine fuel rails for the application...
full standalone engine management - a unit such as the AEM EMS, if you can get it working with the crank signal... all problems solved, with a proper tuner, it will run better than stock...

i'll have my remote mount system complete in 1 - 1.5 years... installing a hand built EMS, i am assembling at the moment, this summer.. full AFR target maps... this thing is going to run a rock solid 12:1 air fuel ratio with no deviation (with the high compression of the NA motor, there is no room for deviation).. the biggest concern i have is capping the stock MAF sensor so it does not see the extra air coming into the system... i want it to think everything is as it was with no turbo...

 

BTW... i tend to agree with the other posters... for you SRT-6 guys, this is not a good idea... there are parts already out there that will give you the extra horsepower you require... twin charged vehicles are not very reliable (just ask the owner of the twin charged MR2 in ultimate car challenge of SCC from two years or so ago) as there are many points that can fail... add the fact that the turbo is hanging by the rear axle... thats one expensive muffler to bottom out on road debris.
but, it is the perfect route for me as this is just what i do and have always done... custom fabrication is my passion/hobby.

 

If you pressurize the intake air, you will still get an increase in the blower discharge, there will be some losses due to slightly lower efficiency of the blower, but there will be a definite net gain. This has been done by a few people on the SLK230 engines. The turbo feeds the blower, can't do it the other way around, it doesn't work. Check the crank pulley on the engine, and see if it's smaller then the one on an SLK 32 if it is get a '32 damper wheel, that will give the blower more rev's and the engine more manifold pressure. One of "our" guys put a bigger crank pulley on his 32 along with some other mods and ended up with LOTS more power. Something like 450 at the rear wheels. That puts a lot of strain on the engine and drive train, so be advised this will cost you in the long run. What kind of intercooler are you running? Is it the same as we have?