You can use the POST_BUILD macro. Add it to the common.mk in the root of your project.

For example:
POST_BUILD=cp blah /tmp

or something like this:

define POST_BUILD
$(RM_HOST) $(HOME)/bin/$@
$(CP_HOST) $@ $(HOME)/bin
enddef

Once the target is built this command will be executed.
Here is the link to the docs: http://www.qnx.com/developers/docs/6.4.1/neutrino/prog/make_convent.html search for 
POST_BUILD.