The easiest way is to update your Viewdraw schematic symbol so it generates the correct Device file for gate/pin swapping to occur.
Attached is a simple example of a Resistor Pack device file generated from Viewdraw which allows gate/pin swapping by using a HETERO Type 4 schematic symbol in Viewdraw. I presented a paper at CDNLive some time ago that talks about the migration from DxDesigner (Viewdraw) Library to Allegro Design Entry HDL Library which is available on the Cadence web site.
Here is a link => http://www.cadence.com/rl/Resources/conference_papers/7.13Presentation.pdf
On Pages 34 thru 38 it explains HETERO Type 4 and how it is used in Viewdraw to allow gate swapping on the Allegro side by generating the Device file and Netlist with functional gates so swapping can occur, also you will have the ability to back-annotation the swaps as well.
Hope this helps,Mike Catrambone