Small Joomla/Virtuemart Textinput Plugin Modification

I need to have one small modification made to the Joomla / Virtuemart AIO Textinput plugin to enable the following: Firstly: The current plugin only allows for a textinput (with a single row) and not a textarea. A modification is required to change this into a Textarea (with say 4-5 rows) where the text can be entered. Instructions need to be given to me of what/where change was made if I want to increase or decrease rows (in backend) This is a easy / small modification to make to those experienced with joomla / virtuemart and the textinput plugin. Further modifications will be required and if the developer delivers satisfactory result it may result in a long working relationship on a pay-per-project basis.