While the Dewalt DW660 will fit in the original/stock mounts, it's much easier to get one parallel and aligned and securely fastened, and ensure the vents are not blocked by using a custom mount as described below.
Created by: User:Improbable Construct
Upgrade Name: DW660
Description: Using the DW660 for your spindle
Status: Fully functional
Materials: 3/8" UHMW, HDPE, or ?
The drawings can be found on github
Tool Free Collar Removal and Spindle Lock Rotation
Use a T15 bit to remove the 4 screws holding the front of the tool together.
You have to hold the tool with the collet UP. If you don't, the entire rotor can fall out of the tool and requires total disassembly of the tool to reinstall.
Once you have removed the 4 screws and the collet nut, the front of the tool comes right off. Remove the snap ring and the tool free collar comes off.
At this point you can also twist the black metal piece and yellow shroud 90 degrees to put the shaft lock on the side with the DeWALT logo.
Removal gives you more room under the tool and makes it much easier to use.
Use a 5/8" wrench to tighten the collet and the stock button to hold the shaft.
Discussion in the forum
Improbable Construct - In use since May 15, 2012
Also note a different design, intended to move the unit closer to the gantry, in a forum post by user zapmaker Yet another set of DW660 mounting brackets (with files).
Also note the use of an even larger Dewalt DWP611 trim router in a forum post by user jzhvymetal here.