This should not be a problem. However, you will be expected to show effective management of the situation. Implementing an efficient, effective ISO 14001 EMS is not easy. To make it worse, most of the key success factors may not be obvious until quite late in the project, if ever. For these reasons, experience is the only thing which really matters.
Technical expertise can be useful.
However, there is a temptation for consultancies with strong technical backgrounds to focus on the issues they feel comfortable with, to the detriment of system efficiency and effectiveness. We prefer to get the implementation right, then buy in any specific expertise as needed. Other than that, look for a consultant who is willing to work with the grain of existing management systems. Beware of companies who will take on only parts of the project, who don't have a sequencial plan, or who only want to provide training. Also beware of companies who want to do expensive gap analyses first.