Hi,
Just a thought, but rather than come out with everything straight away why not do it in stages. I have been weraing ladies g-strings for a few years now and i told my wife fairly early on that i had tried a pair of hers on and that it really excited me. She was surprised at first but now on our 'romantic' nights in together she prefers me to wear them.
Slowly, i have let out that i would like to wear more items (especially lingerie) and she is more accepting, sees it as a bit of a laugh. We also looked at a website together where variuos sexual matters are discussed. One thread was entitled something like "Does your husband wear your panties". As we read through it she saw that lots of other men AND WOMEN liked it, so again that made it easier for her to accept.
Hope this helps,