Modem trouble

Hello, I have a thinkpad with a Xircom windmodem. With RH7.0, I could compile the ltmodem.o module and get the modem working. I have installed kernel 2.4 through Yast when I switched to SuSE this past weekend. The compilation script cannot seem to find the kernel sources. I installed the 2.4 sources. However, it seems to want the sources for kernel 2.4.0-GB4, which is the kernel that is reported by uname -r. The installed sources are labelled 2.4.0.SuSE. Sugestions? John.