Installing a port into a different prefix

[Lennon Cook]

I am attempting to have two ports (java/kaffe and java/jdk15)
installed side-by-side. This means installing one of them into a
different prefix, because they both install several files with the
same name (specifically, java{,c,h,doc} and possibly others). At this
point, I would prefer to do this with kaffe if it is possible. I have
attempted to do this by 'pkg_add -p /opt/kaffe -r kaffe', but this
didn't work: the 'kaffe' binary is installed into /usr/local/bin, and
the various files with conflicting names remain the Sun versions. So,
I tried 'cd /usr/ports/java/kaffe ; prefix=/opt/kaffe make install
clean' , which gave me exactly the same results.

Can anyone enlighten me as to what I'm doing wrong here?

-- 
Lennon Victor Cook
"He who receives an idea from me receives without lessening, as he who
lights his candle at mine receives light without darkening" - Thomas
Jefferson