Just use a GG patch that puts in an earlier version of trose.exe.
There are loads available.
Here is one version that uses the krose version of trose.exe (no gameguard)
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This one uses the older type of packet structure. Different from the packets currently used by NA Rose.
I also have a link to a later type trose.exe that has had gameguard removed from it completely.
Thing is, to use it you will need to modify a lot of packets in your server or you will just get a trose error when you try to connect.