Hello, yes you can take cuttings from Hebe's as i have done many in the past which are now growing in my front garden. I have to say that I am not sure of the correct time to do it but mine always take. I normally do it before they flower, and remove any flowers that are budding.
about a 3" cutting and remove the lower leaves just leave about 4 leaves on the top. have a go and you will see that it works quite well. take a couple more than you need then you will get some right!

I did in the summer, and gave them some bottom heat, although I don't think that's essential. Put the cuttings round the edge of a 1 litre pot and don't pot them on until you see active growth from them, then pot them up individually.

I accidently,broke a stem off mine..a bit over zealous when weeding ! I stuck it in the soil,and it is growing well,so think you should be ok.good luck...