there is no quick way in TurboTax. you need to create 3 returns 1 joint and 2 single/married filing separately.
that's because you may find that the total taxes on the two separate returns is not the same as the taxes on the joint return. even then you have to decide on how "joint" items are to be split such as deductible expenses and joint income if you have dependents on whose return do they go.
the tax programs pros used sometimes can do MFS from a joint return. joint expenses are split 50/50 unless the program allows denoting H,W, or J.
