Remote key synch

I've got an ebay'ed remote key fob I want to synch or add to my car allowing me to open/close it. I'm not going to get the dealer to add the immo bit until I know I can open the doors with it!

I thought it went something like this:-

2 key remotes: 1 old, 1 new.

1. open car and turn ign 1 stop with old key.
2. close door (leaving window open just in case)
3. lock door with new key and press button on new remote <flash/beep>

or is it press old key button for 10s then new key whilst in door twice

or is it stand on one foot.....arrrrgh[]

Anybody got a sensible and reliable guide please?

Once sorted I'll get the key's matched to the immo at Perth Audi (Camerons) -they were the cheaper than two independant dealers who wanted up to 70+vat to match. Cheapest was a VW dealer who'd love to help for just £25 inc vat but said they'd not be thanked by Audi for doing it so couldn't do it.

Cheers,

Matt