FreeBSD install package with prefix

Some packages supports a kind of customisation when compiling with FreeBSD. For example I want to keed track of version of dovecot installed on my system and install dovecot-2.2.10 on its own /usr/local/dovecot2 directory.

I have to run make config-recursive, to select which packages I want to install, and I have to run it as many times needed.

make config-recursive

Then I have to run:
make build-depends-list


install the packages needed as normal and finally install dovecot-2.2.10 in the place I want.

The only thing I have to do is to set the prefix. For example:
cd /usr/ports/mail/dovecot2
cat distinfo

SHA256 (dovecot-2.2.10.tar.gz) = 75592483d40dc4f76cc3b41af40caa4be80478946a699d4 6846d5d03e4d2e09b
SIZE (dovecot-2.2.10.tar.gz) = 4558660
make PREFIX=/usr/local/dovecot-2.2.10 install

If a newer version comes available I will do all the above procedure to check if a new package needed to be installed and then:
make PREFIX=/usr/local/dovecot-2.2.12 install