I don't believe that the Mac will ask you to initialize unless a Mac hard disk driver is on the hard drive and working properly. The driver is something that gets put on the drive behind-the-scenes when you format it with a hard drive formatting program.
If this is a SCSI hard drive, try formatting the drive with the patched HD SC Setup from Gamba:
Download:ftp://grijan.cjb.net:21000/macintosh/So ... ed.sea.bin
( Source: http://home.earthlink.net/~gamba2/hd.html
If this doesn't work, let us know, there are other things you can try too.