If/when you're not connecting to the 1/4" PHONES output on the TD-27 with headphones, then you can use a stereo 1/4" - 1/4" cable and connect the PHONES output on the TD-27 to the V-Drums INPUT [1] on the PM-100.
If you are using the PHONES output on the TD-27, then any standard (mono) instrument cable can be used. Simply connect the L/MONO output on the TD-27 to the V-Drums [1] or LINE[2] INPUT on the PM-100.
These cables can be found at most all music gear retailers.
Note that the sound quality of the PM-100 will be the same using either cable that you choose.