Short answer - not the way SW does it.
Longer answer: You can create a measurement feature that records the distance and use that in a relation to drive the value of an offset from one of the surfaces. The relation will include the measurement in the form DIST:FID_feature_name where the DIST is the name of the measurement in the measurement feature identified as feature_name. You can create your own measurement name and any name you like for the measurement feature. Some measurement features can include multiple measurements.
An alternate is to create a datum curve between the two surfaces and add a datum point at the .500 relative location.
The above methods assume there is something in the middle of the part being placed that can be located. If that is not the case one might have to assemble the part and then create two measurement features, one from each side. Add a relation that takes the difference between the two measurements and then adds that to the offset dimension locating the part. This will require 2 regeneration cycles; the first to roughly place the part and then get the dimensions; the second will take the difference in the dimensions and move the part to where it should be. After that, the dimensions should be equal and the difference will be zero, so another regen will not affect the assembly.
