For 32-bit O/Ses, HGWC cloaks s4client.exe after a certain point (right around the point where xtrap starts up).
You can start it up before then, though:
*Start whichever suspender you use
*Start up s4 League
*When HGWC reaches stage 10/100% in its checks, its box will disappear. You have a short period of time then when you can suspend both HGWC and s4client. One of the suspenders can auto-suspend at this stage in case you're not quick enough or your computer is too fast
*This will only work for certain hacks, since only a small amount of the game is actually loaded. Things that modify multiple game resources, like license hacks to try out unreleased weapons, will only work in the lobby, after the game is loaded, and none of the available suspenders work for the lobby
For 64-bit O/Ses such as Windows XP x64, Vista and Windows 7, because of the different architecture, some current suspenders still work (HGWC doesn't cloak the client yet). In that case:
*Start the suspender you use
*start up s4 League
*Wait until the main window comes up and the game is ~75% loaded, then suspend HGWC and s4client
*Do your editing in CE
*Resume HGWC and s4client
*Hope that you're not disconnected
You can also do your editing in the lobby, but as I understand this carries a higher risk of getting disconnected right away.