is there a way of entering the matches from someones wishlist into a proposed trade? without doing it card by card?

Not yet, but we have some plans for that. :)

I was just thinking about that myself...

Something along the lines of this seems like it should be possible to implement.

1: start a trade with someone.
2: open the wishlist/tradelist card matching screen.
3: select a check box on the left of the match entries you are interested in. These can be entries from both your wishlist and the cards they need from you.
4: hit a button to add 1 of each of the selected cards to the open trade with that person.
5: go into the trade screen and adjust the number for each card if you want more than one.