How to configure non-EUI64 IPv6 addresses with solicited prefixes?

[Darren Pilgrim]

I have two machines where I need them to:

1. Solicit a prefix;
2. Apply the solicitation to a non-EUI64 address;
3. Use the non-EUI64 address as the default source address.

Retaining the EUI64 address is not necessary.  Static configuration 
prevents 1 and I have not been able to get 2 or 3 to work at all.  The 
original KAME documentation implies this is/was possible, but current 
documentation says nothing about it (not that I can find, anyway).  A 
grep of /etc/* indicates interface_ipv6_ifid_* variables (mentioned in 
the KAME documentation) are not supported.

One is running 8.1, the other 6.4 (I can upgrade it if necessary).