What you're going to want to do is have LILO installed on the superblock of the Linux partition, but for it to stay out of the MBR. WinNT and its derivatives (which include XP) don't work very well if they don't use their own bootloader, so the setup you're going to want to have is one where XP detects your linux partition, and not vice versa.
The Slack Book actually has an excellent explanation of the entire process
here where the Windows NT installation is exactly what you're going to want to do for your situation.
In the meanwhile, if you're having trouble getting Windows to boot again (even on its own) you can find a MBR rescue utility at
this page, where you'll need to scroll down to the "EBCD – Emergency Boot CD" section, which advertises itself as useful for botched LILO installs.
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