Altering the counter in an Enumerate

[caspar addyman]

Hi there,

I'd like to be able to divide a list into separate parts but continue  
the numbering. Somewhat like this:

Heading A
        1. something
        2. something else
Heading B
        3. yet another thing
        4. and so on.

I thought I ought to be able to do this with an ERT command   
\setcounter{enumi}{3} in the second enumerate..

but i can't see how to set that before the first (aka third) item.

Any help appreciated,
Caspar