Question : infopath regular expressions

I've been beating my brains out trying to come up with a regualr expression in an Inforpath 2007 password field.
I want to validate the input to require at least one uppercase, one lowercase, and one numeric character and at least 8 characters in length.
I have tried about every pattern that I can come up with and I always get "Invalid Pattern" when entering it in the Custom Patterns box.
Has anyone successfully used a regualr expression in Infopath for what I'm trying to accomplish?

Answer : infopath regular expressions

It should be possible, tedious, but possible.

Here is how I would approach it.
Create 3 fields, true/false, in your form. Capital, Lowercase, Number
1. Validate that it is 8 characters with a pattern comparrison.
2. Create a rule with a comparison expression where password contains, A or B or C or D or....and so on.  Action is set Capital to True.
3. Create a rule with a comparison expression where password contains, a or b or c or d or....and so on.  Action is set Lowercase to True.
4. Create a rule with a comparison expression where password contains, 0 or 1 or 2 or 3 or....and so on.  Action is set Number to True.
5. Create a rule with a comparison expression where Capital and Lowercase and Number are not true Action is password does not validate.

Are you creating a form for Active Directory accounts or some other application authentication?