You can actually load the drivers from the WinPE command line, or use a batch file.
Basically, from the driver perspective, you need drivers that are appropriate for the version of Winpe you are working with. For Ghost Solution Suite 11.5, the WinPE version is 2.x which is based on the Vista kernel and therefore needs Vista 32 bit drivers. If you use a later version of WinPE, Win PE 3 needs Win 7 drivers, up to WinPE 10 which uses Win 10 drivers.
Here are a couple of links for the procedure, and also how to use WinPE 3 with GSS 2.5 if you only have Win 7 drivers available:
https://www.symantec.com/connect/articles/do-i-have-correct-driver-winpe
https://www.symantec.com/connect/articles/creating-and-using-winpe31-image-gss-251
Or you have the option of upgrading to Ghost 3.x which also adds support for things like UEFI bioses which Ghost 2.5 does not function under, and uses a much newer version of WinPE.
Bear in mind also, that modern hardware may also require you to add drivers to WinPE for both the NIC and the SATA chipsets, especially for old versions of WinPE which were released well before these chipsets were manufactured.