This effect is easy peasy in Fireworks. All you need to do is use a linear gradient and adjust the gradient. Let's try this with black and white.
Apply a black/white linear fill to the text. Click on the Edit button in the Fill panel to open the Gradient Editor pop-up.
Drag the black chip to the center of the space, then drag the white chip directly on top of the black one.
There's our two tone text. Note: to save it as a Fireworks style, select the text and click on the right arrow button at the top right of the Styles panel. Choose New Style from the menu. In the dialog box that pops up, give the Style a name and check off the elements that apply.
Rotate the gradient so the black half is at the top of your text. I've also added my two tone style to a rectangle behind the text, but with the colors inverted.
Hmm. I see some masking potential there. I'll show you what I mean.
In Fireworks 4, choose Edit > Select All, and then Modify > Convert to Bitmap. Open a photo in Fireworks. Copy the two tone text bitmap and paste it on top of the photo. Move it to the area of the photo you would like to mask then choose Edit > Select All, and then Modify > Mask > Group as Mask.
Wherever the black parts of the text image mask the photo, the photo shows through. The white parts remain opaque white.
To achieve the same mask effect in Fireworks MX, reverse the gradients so the the top of the text is white and the bottom of the two tone rectangle is white.