I've done some more work on this now and checked the tutorial you gave me which lead me to some others as well.
I feel I could create a g3 360 character by importing the right file and adding the bone structure.
However, I'm not capable of creating the actual character.
I purchased some 3d characters from the store https://www.reallusion.com/ContentStore/ccdproduct.html?contentid=ACR300CIENU000020171106001
and they're ok but the look I'd really like to get is similar to 'Red' that comes with CTA4.
I need some businessmen and businesswomen for some training videos I'm producing hence the desire for the higher quality.
I've had some live chats with the store support but not found what I'm looking for, so I wondered if you knew of places/people I could either get the completed characters or download files that I could then import to CTA4 and create the bone structure for?
I know you have a marketplace but I haven't managed to find it there either.