Is there any trick that allows to use Management Studio's (ver. 2008) IntelliSense feature with earlier versions of SQL Server?
Aside from using a third party tool, no. I run into this problem a lot too. The deal is the SqlServer2005 doesn't support the meta data to do that.

However, I can suggest (cos I used it for a bit and loved it) RedGates SqlPrompt product to do this. It's incredibly handy. However, it does cost money, so there's a tradeoff.

If someone DOES have a workaround for this, I would love to hear of it.