There is a way ( or I'm mistaking ? I think the way I'm explaining is for max_map_miptex)
The default texture data limit is aprox 4MB . You can increase that limit . Type at the hlcsg parameters box this : "-texdata #" ( where "#" is your number ) without the quotes .
The texture limit is expressed in Kilobytes not Megabytes ( i.e for 15 MB the number will be 15000 aprox. because 1MB=1024 KB )
Don't type a very high number . Why ? The map won't work on old computers . (i.e if you type 128000 which corresponds to aprox 128 MB , the compiled map won't work on computers with a video card memory of 64 MB )