I am a little confused using this driver in a 2 way set-up. I am sure you are aware, this is a midrange driver. Even though the specifications say it will go to 9000hz, it falls flat on its face after 5000hz. If you are building a traditional 2-way (woofer/tweeter), I would return this driver and get a Selenium D220TI HF driver.
To answer your question, it depends which type of horn you are using and your woofers performance. . The minimum crossover point for this driver is 500Hz and you can use a Eminence PXB2:800 with a Selenium HL 14-25 or HL 23-25 horn. Both horns are rated at 600 min crossover and you will be crossing over at 800hz. Almost all woofers will do 800hz no problem.
If you got the wrong driver and switch to a D220TI, then we need to move the crossover point up to 1500hz. An Eminence PXB2:1K6 will work nicely with a Selenium HM 11-25 or HL 25-25 horn. Both horns are rated at a 1200 min. crossover. It will also work nicely with the above horns as well. Most high quality woofers will do 1500-2000hz, so depending on your woofers quality and performance, you should be ok. The D220Ti is good from 1500hz to 20,000hz.
Hope this answers your questions.