I want to reskin some sleeves, I've got a picture of a German paratrooper camosmock, I want to use this for my own sleeves, but I am a noob on rekinning and I want to know how to do that, is there a tutorial or something on the web, or can someone help me???

send me the photo (or a link) and I'll do it for you if you want.

or if u want to DIY, open any model in hlmv, then go to textures, and export the axis sleeve tex. then using photoshop, edit the skins, then save the new version, import it and then save the model.

But I've got some free time and I would like a challenge so...

hint hint...

I just have a picture (photo) of a splintercamouflage pattern, and I want to put that over the default one, but I don't know how to do that in Photoshop, cuz I wanna keep the wrinkels, shadows, highlights from the default sleeve, cuz they r nice, but when I do copy paste the wrinkels etc the default skin shows through, can anyone give me a tip please, I am such a noob with modelling and I wanna learn!

Put the cammo pattern over the sleve in another layer, then experiment with layer effects for blending the two, overlay or color would probably be your best bet.

heres the long explanation:
1.Open up HLMV
2.Select a weapon, and scroll down to the axis sleaves.
3.Export the axis sleave skin
4.Open it up in photoshop
5.paste your texture over the dod one
6.choose an opacity/fill that suits you, or, if youre a little more skilled, just paste it over and redo all the folds/creases.