Ehoehn,
I should add one thing: You have to want to do this.
There are a bunch of parameters that can (and - for optimal results - must) be varied for the sub's high cut function, while the trial/error process with parametric EQ is (almost) infinitely variable and extremely time consuming. There are LOTS of combinations to try and many, many test runs will be checked and rejected before you find a satisfying mix. Then you can start tweaking.
Being the somewhat compulsive type, I actually developed a taste for the process. (I'm pretty sure that there is treatment available for this.) If this doesn't sound appealling, I'd say that the SMS isn't for you.
If you follow through, it is rewarding. OTOH, the SVS/Audyssey box (more sophisticated auto calibration) probably gets you to substantially the same place with a LOT less work (although it costs a fair bit more). Different courses...
Good Luck
Marty