Actually, it's supported already.
The latest pcmanfm/libfm supports DES-EMA.
http://www.nautilus-actions.org/?q=node/377
You can install custom actions with this.

On Sat, May 12, 2012 at 12:55 AM, Jarno Suni <jarno.ilari.suni@gmail.com> wrote:
One thing I miss most in PCManFM is Thunar's custom actions, although
custom command line open feature helps a lot.