Change portfolio_item slug to something else

Hi i created a portfolio using portfolio categories in theme, i added some entries on it trying to make it look like a catalog, the entries has this kind of URL’s:

Portfolio Category:
Cajas de cartón

Slug:
cajas-de-carton

Example:

http://www.cajas-empaques.com/portfolio_item/caja-de-carton-estandar-corrugado-sencillo-modelo-45/

i would like that it look like this for all the items in that category

http://www.cajas-empaques.com/carton/caja-de-carton-estandar-corrugado-sencillo-modelo-45/

also i have would like to make the same for the English section for example the next URL:

Category:
Cardboard boxes

Slug:
cardboard-boxes

Example:

http://www.cajas-empaques.com/en/portfolio_item/caja-para-pizza-de-carton-troquelada-de-corrugado-sencillo/

i would like that the items have an url like this

http://www.cajas-empaques.com/en/cardboard/caja-para-pizza-de-carton-troquelada-de-corrugado-sencillo/

could you helpe with this? is the only thing left to left to finnish my website