[Dr!fter]

You can do this with dhooks

clientprintf-hook.games.txt

"Games"
{
	"#default"
	{
		"Keys"
		{
			"EngineInterface"	"VEngineServer021"
		}
		"Signatures"
		{
			"CreateInterface"
			{
				"library"		"engine"
				"windows"		"@CreateInterface"
				"linux"			"@CreateInterface"
			}
		}
		"Offsets"
		{
			"ClientPrintf"
			{
				"windows"	"45"
				"linux"		"45"
			}
		}
	}
	"csgo"
	{
		"Keys"
		{
			"EngineInterface"	"VEngineServer023"
		}
		"Offsets"
		{
			"ClientPrintf"
			{
				"windows"	"46"
				"linux"		"46"
			}
		}
	}
}

clientprintf-hook.sp

PHP Code:

#include <sourcemod>
#include <dhooks>
#include <sdktools>

new Handle:hClientPrintf = INVALID_HANDLE;

public OnPluginStart()
{    
    new Handle:gameconf = LoadGameConfigFile("clientprintf-hook.games");
    if(gameconf == INVALID_HANDLE)
    {
        SetFailState("Failed to find clientprintf-hook.games.txt gamedata");
    }
    new offset = GameConfGetOffset(gameconf, "ClientPrintf");
    if(offset == -1)
    {
        SetFailState("Failed to find offset for ClientPrintf");
        CloseHandle(gameconf);
    }
    StartPrepSDKCall(SDKCall_Static);
    if(!PrepSDKCall_SetFromConf(gameconf, SDKConf_Signature, "CreateInterface"))
    {
        SetFailState("Failed to get CreateInterface");
        CloseHandle(gameconf);
    }
    
    PrepSDKCall_AddParameter(SDKType_String, SDKPass_Pointer);
    PrepSDKCall_AddParameter(SDKType_PlainOldData, SDKPass_Pointer, VDECODE_FLAG_ALLOWNULL);
    PrepSDKCall_SetReturnInfo(SDKType_PlainOldData, SDKPass_Plain);
    
    new String:interface[64];
    if(!GameConfGetKeyValue(gameconf, "EngineInterface", interface, sizeof(interface)))
    {
        SetFailState("Failed to get engine interface name");
        CloseHandle(gameconf);
    }
    
    new Handle:temp = EndPrepSDKCall();
    new Address:addr = SDKCall(temp, interface, 0);
    
    CloseHandle(gameconf);
    CloseHandle(temp);
    
    if(!addr)
    {
        SetFailState("Failed to get engine ptr");
    }
    
    hClientPrintf = DHookCreate(offset, HookType_Raw, ReturnType_Void, ThisPointer_Ignore, Hook_ClientPrintf);
    DHookAddParam(hClientPrintf, HookParamType_Edict);
    DHookAddParam(hClientPrintf, HookParamType_CharPtr);
    DHookRaw(hClientPrintf, false, addr);
}
public MRESReturn:Hook_ClientPrintf(Handle:hParams)
{
    new client = DHookGetParam(hParams, 1);
    decl String:buffer[1024];
    DHookGetParamString(hParams, 2, buffer, sizeof(buffer));
    PrintToChat(client, "BUFFER %s", buffer);
    return MRES_Ignored;
} 


Requires DHooks and latest SM 1.5 snapshot.

Of course the drawback to using DHooks is you need gamedata and code to grab the engine pointer. But felt this would be helpful example. The example only supports csgo and css but only tested on css.