The best ways to do this probably wouldn't be with a statically configured IPv6 tunnel service such as HE, or really, any service which requires an account to be set up, etc.
It'd probably be best to rely on SLAAC (StateLes Address Auto Configuration), which is built into IPv6, and/or DHCPv6 as the "preferred" way of obtaining IPv6 info. That way if IPv6 is already running on the particular network infrastructure you come up on, it will use that, as is proper.
If it comes up on an IPv4 only network, then one could attempt to use Teredo or 6to4 to get IPv6 going. Both of these do not require any previous setup to establish an IPv6 tunnel, both being automatic tunneling methods. 6to4 would be much more difficult to implement in an automatic fashion, and since it's based on 6in4, it doesn't play well behind IPv4 firewalls/NAT (for instance, forget about having more than one 6to4 client behind a single public IP NAT situation).
Teredo has more overhead than 6to4, and is byzantine in its operation compared to 6to4, but is basically completely automatic. It's been implemented under Linux via the Miredo software. Basically, once you turn it on, it determines its Teredo IPv6 by talking to various Teredo servers on the internet, and IPv6 traffic is encapsulated in UDP and relayed via various Teredo relays (which are different from Teredo servers) on the internet, or "directly" to other teredo clients using UDP hole punching. Like 6to4, the Teredo IPv6 is determined by the public IPv4. But since the IPv6 packets are encapsulated in UDP, it plays nice behind NAT devices/firewalls.
So this would be by far the easiest way to establish an IPv6 island in an IPv4 sea. The problem with Teredo I've found is that it can have slow startup, and a bit of overhead can lead to fairly slow RTTs. But it generally works.
BTW: HE runs many Teredo relays on the internet. I believe nearly all their tunnel servers are also teredo relays (or have teredo relays present in the same PoP). Tracing Teredo traffic from where I've been spending the holidays, I've noticed that large portion of my Teredo packets go straight to an HE relay.